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Advice on fixing a nearly chopped Supercat 15 bow

Posted By: Luiz

Advice on fixing a nearly chopped Supercat 15 bow - 10/19/10 02:05 AM

Yesterday I pitchpoled the Boston Whaler SuperCat 15 I recently restored in exchange for its use.

It was blowing around 30 knots and we were fighting for the lead ahead of bigger cats, but it wouldn't be worth mentioning here if the mast base wouldn't brake its "neck" and, more important, the inside of the bow side near the mainbeam wouldn't crack open.

I guess the two damages are related. The loosened mast base may have hit the side of the bow and caused the crack, but I don't know for sure, all I could see was water smile

Anyway, the bow damage extended further when the boat was slowly towed to shore upside down and backwards, with the severed bow slightly up to keep it from flooding or breaking too fast. The wind was getting stronger, so it wasn't an easy task.

In the end the bow was nearly separated from the rest of the float at about 5 to 10 inches forward of the main beam. I need advice and suggestions to fix this.

The repairs will be done by a local shipyard that mostly builds motor boats and canoes. They know even less than I do about light cats - and I certainly don't know enough, at least not for a breakage of this magnitude.

Thanks for helping.
Posted By: TheManShed

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/19/10 03:38 AM

Wow another one. A supercat 20 broke up with similar damage off of Palm Beach. It was a total loss after spending a night adrift then beaching. Foam / fiberglass construction is a bit tricky to fix if they are not use to it. Did it break forward of the bulkhead? Pictures?
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/19/10 04:46 AM

Originally Posted by TheManShed
A supercat 20 broke up with similar damage off of Palm Beach. It was a total loss...
Did it brsdeak forward of the bulkhead? Pictures?


Our's didn't sink because we were just one mile away, it took about an hour to tow it to shore.

From memory the crack is 5 to 10 inches forward of the main beam. I never saw the inside of a Supercat, didn't look inside the crack and don't know if the SC15 has a bulkhead. Do you know where it is supposed to be?

When I find time to tow the boat to the shipyard, I'll bring a lantern and camera to search for the bulkhead and take the necessary pictures. Yesterday I only had time to disassemble the boat for transport before it was dark, no time to take pictures, even if I had a camera with me.


Posted By: erice

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/19/10 07:18 AM

ouch! there are a few pics about of snapped off supercats bows, maybe they can be dug up here?
Posted By: cyberspeed

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/19/10 01:14 PM

In the SC 20, the bulkheads are under the main beam and under the rear beam. If where the bulkheads are glued to the hull crack, it could cause the front of the boat to weaken.

From your first post, the weakend front bow is not the problem. It just sounds like the mast took it out after the base snapped off.
Posted By: tomthouse

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/19/10 02:13 PM

You may wish to contact Tom Haberman at Aquarius Sails.

E-Mail: info@aquarius-sail.com or sales@aquarius-sail.com

Telephone: 651-462-SAIL (7245)

FAX: 651-462-7245


For years, they used to sell, sail and maintain these boats.

If memory serves me, they may have even been heavily involved in the design and manufacturing of them, or they were closely associated.

Great folks and they have treated me very well over the years with information, parts, advise and suggestions.

It would be worth the call or email.

If you find out anything, let us know.

What you find out may help when something goes wrong with some of these other Supercats, that are still on the water.

If you call, say hello to Tom from Tom House in Utah.

I am continuing to sail the sox off my supercat 17 and my 474 Freestyle (15 footer).

Boy have I had fun with that Suercat 17 on lakes and during coastal adventures around southern California and Catalina Island.

Is life good or what....
Posted By: cyberspeed

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/19/10 02:47 PM

Aquarius Sails still supports the Supercats line. Tom would be a great person to contact. They will also have any of the parts if you need them.

I think a contributing factor with the SC 20 that TMS was talking about was the boat was moored on the water for a few years at the least, could be some sort of water saturation. I almost bought that boat. Glad he renigged on my origional offer.

Also did not help that they took it out in a Topical Storm watch.
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/19/10 04:10 PM

If there's a bulkhead under the mainbeam, I believe the breakage is located close to where the glass reinforcements keeping the forward bulkhead in place end, the most likely place for such a rupture.

If I was in the US I would simply send the hull to Aquarius Sail to be fixed, but we are on the other hemisphere, many thousands of miles away... it is good advice, though, so after I take the pictures I'll write to Tom Haberman and/or Bill Roberts to see if they can help.

All the best,
Luiz
Posted By: TheManShed

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/23/10 04:56 PM

Usually there is some type of bulkhead / support under the main beams to transfer the loads from the beam / rig to the hulls. If you want to see inside the hull of the SuperCat take a look here http://themanshed.net/archived-projects/supercat-20/?g2_page=1 This is taken in my shop.
Back in the day I use to go to Bill's shop and see what he was working on when he was still building the boats and molds in Palm Beach County. Basically anything can be fixed but you have weigh the cost vs the price vs the time. If you have the time, skill or the willing to learn, and place to work on it is not too bad of a job. Although repair work is not as easy as an experienced person makes it look. I enjoy it but I’ve also restored old cars in the past and find it a way to spend some time when not sailing.
The other option is if you are paying somebody to do the work keep in mind time vs work = profit. Make sure they do it correctly and not just make it look pretty. It may be cheaper to replace the hull with a used hull. Like cyberspeed says did the mast take it out or failure of the hull? Make sure you check the other hull out before you go back on the water.
Good Luck!
Posted By: TheManShed

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/23/10 05:04 PM

Originally Posted by cyberspeed
I almost bought that boat. Glad he renigged on my origional offer.


So am I my shop is already getting full! cool
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/24/10 03:30 AM

Originally Posted by TheManShed
Usually there is some type of bulkhead / support under the main beams to transfer the loads from the beam / rig to the hulls. If you want to see inside the hull of the SuperCat take a look here http://themanshed.net/archived-projects/supercat-20/?g2_page=1 This is taken in my shop.
Back in the day I use to go to Bill's shop and see what he was working on when he was still building the boats and molds in Palm Beach County. Basically anything can be fixed but you have weigh the cost vs the price vs the time. If you have the time, skill or the willing to learn, and place to work on it is not too bad of a job. Although repair work is not as easy as an experienced person makes it look. I enjoy it but I’ve also restored old cars in the past and find it a way to spend some time when not sailing.
The other option is if you are paying somebody to do the work keep in mind time vs work = profit. Make sure they do it correctly and not just make it look pretty. It may be cheaper to replace the hull with a used hull. Like cyberspeed says did the mast take it out or failure of the hull? Make sure you check the other hull out before you go back on the water.
Good Luck!


Thanks Mike,

I can certainly see the inside of the SC15 hull now... This Sunday I'll tow it to the shipyard and take some pictures to post here.

That hull was leaking since the boat was painted and we never found where the leak was. It may have been structural, as you said. The other hull is 100% watertight and seems to be solid. I can't check its inside without opening a hole, though.

I am not skilled enough to repair this by myself, but the guys at the shipyard aren't that bad. My concern is their lack of experience with foam sandwich and what technique is best. I guess it is better to discuss this with the pictures.

Meanwhile, I already had the mast base welded and made a new tiller crossbar.

Cheers!
Posted By: Hullflyer1

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/24/10 12:41 PM

Would it not be easier to try and locate a used hull?
Posted By: Todd_Sails

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/24/10 01:21 PM

I've seen several boats of different manufacturers become weak and begin to fail just ahead of the main beam.

I think it comes from years of the loads just ahead of the main beam, flying ah hull. Then, a semi violent pitchpole adds even more stress to the area just ahead of the main beam.

My Prindle 18-2 began to fail just ahead of the main beam as well. I've seen others.

Good luck, sounds like you'll get it fixed just fine.
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/24/10 11:55 PM

Originally Posted by Hullflyer1
Would it not be easier to try and locate a used hull?


Yes it would and that's what I'd do if I was in the US.
All six SC15 in the country are in very decent shape, racing as a one design class. Only one wasn't at the race when I pitchpoled.
Posted By: Luiz

Advice on fixing a nearly chopped SC15 bow - PICTURES - 10/25/10 12:26 AM

This week I had the mast foot welded (about USD 30), sewn and taped the batten pocket, made a replacement tiller cross arm and replaced the broken battens with their spares.

Today I trailed the SC15 to the shipyard, together with two Lasers from the sailing school that also need repairs.

The shipyard owner is considering four alternatives:

a) Open the entire hull longitudinally, fix each side and glue them back. This allows the entire hull to be inspected and fixed, but is time consuming (expensive) and probably adds weight.

b) Open longitudinally from the bow to the crowwbeam and chop off the inside half only. With good access to both sides of the bow, it can be properly fixed and glued back in place with minimal extra weight. This is simpler and faster, but we can't inspect the entire hull.

c) Take molds of the damaged part (or the entire bow) from the other hull and laminate a new section to glue in place. This seems complicated and we can't inspect the entire hull.

d) Take moulds from the other hull and make a new hull. This is expensive and requires permission from the designer, but would yield the best result - at the highest cost.

What do you think?

Thanks!

Attached picture P1080311.jpg
Attached picture P1080314.jpg
Attached picture P1080315.jpg
Posted By: rturbett

Re: Advice on fixing a nearly chopped SC15 bow - PICTURES - 10/25/10 01:44 AM

The Best way to fix this boat if you plan on racing it is to locate another hull. Every other way will add weight.
The way I would fix it is to cut a large (six inch wide by length of the top crack ) hole in the top of the hull.
debur the crack from the inside so that the forward portion lines up correctly, and any questionable core is cleared out. Take a high build fiberglass mat (I like the multi layered one with the spheres in it) soaked in epoxy and line the inside of the hull as far back and as far forward as you can reach.
then do a normal hole repair for the top.
Lots of professional repair advice on Boatdesign.net

Rob
Posted By: cyberspeed

Re: Advice on fixing a nearly chopped SC15 bow - PICTURES - 10/25/10 01:26 PM

Did the hull bend inward or is it just cracked. Looks like the mast just came down on it and cracked it which is better than the bow bending in.
Posted By: Luiz

Re: Advice on fixing a nearly chopped SC15 bow - PICTURES - 10/25/10 01:36 PM

Originally Posted by rturbett
The Best way to fix this boat if you plan on racing it is to locate another hull. Every other way will add weight.
The way I would fix it is to cut a large (six inch wide by length of the top crack ) hole in the top of the hull.
debur the crack from the inside so that the forward portion lines up correctly, and any questionable core is cleared out. Take a high build fiberglass mat (I like the multi layered one with the spheres in it) soaked in epoxy and line the inside of the hull as far back and as far forward as you can reach.
then do a normal hole repair for the top.
Lots of professional repair advice on Boatdesign.net

Rob


A simple and practical solution, thanks!

Extra weight, however undesirable, is not a major concern. All the SC15s are old, therefore overweight due to repairs. Added weight will keep it within the one design parameters.

Besides, the skippers here can save a lot more weight with a diet than optimizing repairs... their average weight is around 100 kg / 220 lb! (my weight!)
Posted By: Luiz

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/25/10 08:50 PM

Reviewing old pictures taken before the recent gelcoat remake, I found indications that the bow failed due to pre-existing delamination problems.






Description: Upside down hull with a line showing delamination or something similar.
Attached picture upsidedown bow.jpg

Description: Detail of upside down float with bump, probably caused by glass detaching from foam.
Attached picture probable delamination.jpg
Posted By: TheManShed

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/26/10 05:53 AM

Looks like it was coming apart before the crack by the buckle in the hull. I’d take a jig saw and cut away the bad glass plus about 5” on each side in a rectangle shape. On the other hull, the good one in the same location prepare the hull with duct tape then wax to use as a mold. The hulls are pretty much symmetrical so the patch from the outside of the good hull will be for the inside of the bad hull……….so forth. I would also use Epoxy and not poly resin. I don’t recommend mat - no strength, use a biax and make one or two lay-up patch with about 4” larger than the damaged area. This will be your patch panel. I’d make 2 or 3 pieces that is a port , starboard, and deck patch.. Make one patch panel for each side and one for the deck. They will bend some so you can fit them inside the hull. Scuff the inside of the hull to get a good clean bite. Make sure all the wax is removed from the molding process. Clamp the panels in place and let dry. Also inspect the inside of the hull for any other damage before you seal it up and make sure bulkheads are attached to the hull. The seam is splitting to it needs to be ground smooth, filled and glassed over from the inside, and outside Taper the outside of the repair area then you can glue in foam or make a solid patch, and put your outside skin and finish. . West system has a short video on the repair of foam/fiberglass that covers the basics http://www.westsystem.info/wesyephodvd.html . I have some pictures of similar repair not as big and I used the cut out piece but the same idea http://themanshed.net/archived-projects/g-cat-catamaran/?g2_page=2 and http://themanshed.net/archived-projects/g-cat-catamaran/?g2_page=3
On the Supercat 20 I had to make a piece for the deck where a funky wood top patch was made. I made a temp mold of the other port hole and deck area, had to spin it 180 and correct the angle. http://themanshed.net/archived-projects/supercat-20.html Since you are close to the bulkhead make sure you do not cut into it and you can tie your patch into the bulkhead to make it stronger. Back then I used bondo type products for faring and have since removed all of it. Do not use plastic fillers they asorb water, it is best to make an epoxy paste with a filler it is a little harder to sand but much better.

I would not use the old piece of the SuperCat15 since it was failing and check out the skins around the cut-out to make sure it is sound.

It is getting late I worked too late in my shop so I need to turn in if you would like more detail you can contact me directly.
Posted By: Luiz

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/26/10 04:22 PM

Originally Posted by TheManShed
Looks like it was coming apart before the crack by the buckle in the hull. I’d take a jig saw and cut away the bad glass plus about 5” on each side in a rectangle shape. On the other hull, the good one in the same location prepare the hull with duct tape then wax to use as a mold. The hulls are pretty much symmetrical so the patch from the outside of the good hull will be for the inside of the bad hull……….so forth. I would also use Epoxy and not poly resin. I don’t recommend mat - no strength, use a biax and make one or two lay-up patch with about 4” larger than the damaged area. This will be your patch panel. I’d make 2 or 3 pieces that is a port , starboard, and deck patch.. Make one patch panel for each side and one for the deck. They will bend some so you can fit them inside the hull. Scuff the inside of the hull to get a good clean bite. Make sure all the wax is removed from the molding process. Clamp the panels in place and let dry. Also inspect the inside of the hull for any other damage before you seal it up and make sure bulkheads are attached to the hull. The seam is splitting to it needs to be ground smooth, filled and glassed over from the inside, and outside Taper the outside of the repair area then you can glue in foam or make a solid patch, and put your outside skin and finish. . West system has a short video on the repair of foam/fiberglass that covers the basics http://www.westsystem.info/wesyephodvd.html . I have some pictures of similar repair not as big and I used the cut out piece but the same idea http://themanshed.net/archived-projects/g-cat-catamaran/?g2_page=2 and http://themanshed.net/archived-projects/g-cat-catamaran/?g2_page=3
On the Supercat 20 I had to make a piece for the deck where a funky wood top patch was made. I made a temp mold of the other port hole and deck area, had to spin it 180 and correct the angle. http://themanshed.net/archived-projects/supercat-20.html Since you are close to the bulkhead make sure you do not cut into it and you can tie your patch into the bulkhead to make it stronger. Back then I used bondo type products for faring and have since removed all of it. Do not use plastic fillers they asorb water, it is best to make an epoxy paste with a filler it is a little harder to sand but much better.

I would not use the old piece of the SuperCat15 since it was failing and check out the skins around the cut-out to make sure it is sound.

It is getting late I worked too late in my shop so I need to turn in if you would like more detail you can contact me directly.


Excellent, many thanks!!!
I'll translate it to the shipyard owner and will be back with the doubts, if any.

In "I would not use the old piece of the SuperCat15 since it was failing" you mean the parts (scraps) cut around the failure area?

Cheers,
Luiz

Posted By: TheManShed

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/26/10 05:12 PM

Yes

One thing to remember the hull is strong by the construction.
Inside skin /foam layer/ outside skin. They must be in 100 % contact and overlap in the repair making one single inside skin / foam layer / outside skin structure clear of any voids.
Posted By: sail7seas

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/26/10 08:18 PM

Please look at the bottom of the attached hyperlink.
You will observe the highest stresses are just away from the fixed support, when displacement is added.
http://web.mit.edu/calculix_v2.0/CalculiX/ccx_2.0/doc/ccx/node6.html

Oversimplifying the hull in front of the main beam acting as a cantilever, from statics the highest shear, bending moment, and torsion occurs at the main beam,
with the least rate of displacement due to bulkhead/reinforcement.

Traveling just a little ways from the main beam there is not only high bending, shear & torsion, but now add rate of displacement.
Cyclic section distortion (sans bulkhead) as the hull displaces under load (in,out,& twist) compress & uncompress the foam, as the fiberglass inner and outer skin is 10x stiffer than the foam.
The inner & outer layer move at different rates to accommodate hull distorsion, the foam eventually looses the battle.
The '70s Tornados added a bulkhead in front of the main beam for reduction of hull distortion/stress & bow deflection.
Posted By: Luiz

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/26/10 08:34 PM

Understood.

Closed cell foam is not available here. The alternatives are:

1) Recover foam from the cutout (it seems to be in good shape), glue the bits with epoxy over a thin layer of glass and reuse.
2) Wood. Planks, ply or laminated are easy to find. Heavier.
3) Glass mat. Makes a thik solid laminate. Heavier.
4) Styrofoam (high density). The repair doesn't extend to the keel, it is mostly above the waterline and the boat is never moored.
5) Open cell polyuretane foam (insulation type)

6) Combinate two or more. Maybe a few wood (or glass) battens laid longitudinally, with strips of recovered foam between them?

I can buy a PVC foam plank, but if they can't be forwarded by plane, it'll take about three months to arrive (planks ship truck only, apparently).
The foam appears to be 4 mm (5/32) thick, does this sound right? Brand and density unknown. Color is like sand - check the picture.

Thanks!


Description: Detail of delamination with foam color visible.
Attached picture SC15 foam color.jpg
Posted By: Luiz

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/26/10 08:42 PM

Originally Posted by sail7seas

Please look at the bottom of the attached hyperlink.
You will observe the highest stresses are just away from the fixed support, when displacement is added.
http://web.mit.edu/calculix_v2.0/CalculiX/ccx_2.0/doc/ccx/node6.html

Oversimplifying the hull in front of the main beam acting as a cantilever, from statics the highest shear, bending moment, and torsion occurs at the main beam,
with the least rate of displacement due to bulkhead/reinforcement.

Traveling just a little ways from the main beam there is not only high bending, shear & torsion, but now add rate of displacement.
Cyclic section distortion (sans bulkhead) as the hull displaces under load (in,out,& twist) compress & uncompress the foam, as the fiberglass inner and outer skin is 10x stiffer than the foam.
The inner & outer layer move at different rates to accommodate hull distorsion, the foam eventually looses the battle.
The '70s Tornados added a bulkhead in front of the main beam for reduction of stress & deflection.


Yes, the risk of skin/foam detachment is higher in this area - and this is what happened.
Posted By: dacarls

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/26/10 09:22 PM

Hi Luiz,
I bought small sheets (0.5 m x 0.5 m) of stiff polyurethane foam 4 to 6 mm thick from internet contacts in the USA. It was sent by UPS to me ok. No large-scale "shipping".
Posted By: David Parker

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/27/10 01:49 AM

Originally Posted by erice
ouch! there are a few pics about of snapped off supercats bows, maybe they can be dug up here?


Here's a little SC-17 hull damage. It looks like this one was helped along by too much dragging the hull up the beach. That "sanded off" the seam along the bottom.

A little epoxy, a little duct tape, and it's back on the water, eh?
"Tis but a scratch" (Monty Python, Black Knight)

Attached picture SC - Hull 1.jpg
Attached picture SC - Hull 5.jpg
Posted By: Luiz

Re: SC15 bow - PICTURES BEFORE RECOATING - 10/27/10 11:55 PM

Originally Posted by dacarls
Hi Luiz,
I bought small sheets (0.5 m x 0.5 m) of stiff polyurethane foam 4 to 6 mm thick from internet contacts in the USA. It was sent by UPS to me ok. No large-scale "shipping".


Interesting. Any details, like if it is closed cell, the density and price?
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/28/10 12:15 AM

Originally Posted by David Parker

Here's a little SC-17 hull damage. It looks like this one was helped along by too much dragging the hull up the beach. That "sanded off" the seam along the bottom.

A little epoxy, a little duct tape, and it's back on the water, eh?
"Tis but a scratch" (Monty Python, Black Knight)



Do you know if this one was fixed or scapped?

Ours just looks better, but in fact only the keel and half of one side keep the bow from falling apart. I can probably break it using my hands only.
Posted By: erice

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/28/10 12:24 AM

in the usa you wouldn't fix that
you would either part it out and recover most of the boats cost
buy another hull
or buy another supercat
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/28/10 01:57 AM

Originally Posted by erice
in the usa you wouldn't fix that, you would either part it out and recover most of the boats cost, buy another hull or buy another supercat


Right, much like you do with the cars, they are saved only when truly loved by the owner, which could be the case, I guess.

Here we have different price structure, tax regime, labour costs and availability of parts/boats. As a consequence, the rational decision is often different, even if the boat's state is about the same.

Cheers,
Posted By: carlbohannon

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/28/10 02:39 PM

The advice you are taking looks very good. I like to add a couple of things. Tell the yard:

The taper on the original hull were it meets the patch should be 8-10 to 1 and I would use light (2-3 ox/yd) cloth for the repair.

They should seal the foam as a separate step after the taper, coat with epoxy and let it dry before you add anything else.

A good core material for this type of repair is core mat:

http://fiberglasssupply.com/Product_Catalog/Core_Materials/core_materials.html

It can folded like cloth so shipping costs are reasonable. I was told once that you can make something similar by coating both sides of ~1 oz/yd fiberglass with epoxy micro balloons. The epoxy micro balloons mixture should be what West Systems calls peanut butter thick. I have not tried this since core mat is cheap for me.

My personal preference is to use Kevlar for the inner patch. Kevlar tends to hold even after glass or carbon cracks. I have made it to shore twice because I used a layer of Kevlar in my laminate.

Good Luck
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/28/10 04:46 PM

Originally Posted by carlbohannon
The advice you are taking looks very good. I like to add a couple of things. Tell the yard:

The taper on the original hull were it meets the patch should be 8-10 to 1 and I would use light (2-3 ox/yd) cloth for the repair.

They should seal the foam as a separate step after the taper, coat with epoxy and let it dry before you add anything else.

A good core material for this type of repair is core mat:

http://fiberglasssupply.com/Product_Catalog/Core_Materials/core_materials.html

It can folded like cloth so shipping costs are reasonable. I was told once that you can make something similar by coating both sides of ~1 oz/yd fiberglass with epoxy micro balloons. The epoxy micro balloons mixture should be what West Systems calls peanut butter thick. I have not tried this since core mat is cheap for me.

My personal preference is to use Kevlar for the inner patch. Kevlar tends to hold even after glass or carbon cracks. I have made it to shore twice because I used a layer of Kevlar in my laminate.

Good Luck


Great advice Carl, thanks!
My boat's floats used coremat as buildup between coats for increased stiffness in some points.
Tomorrow I'll meet with the guys in the shipyard and make the final plan - and will post it here, obviously.

Cheers,
Posted By: basket.case

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/28/10 10:54 PM

http://www.noahsmarine.com/
just order 1 sheet of the proper sized corecell, contour cut.
Posted By: TheManShed

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/29/10 02:05 PM

As you can see everybody has ideas on how to fix it. You have to trust the person doing the work to blend the ideas.
My thought...Kevlar good on the inside doesn't sand well so it's good for an inner wet lay-up. Coremat I've used it for bulk and some stiffness no strength. Foam use boat build quality nothing else. Wood - never.

Good luck
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/30/10 02:24 AM

Originally Posted by TheManShed
As you can see everybody has ideas on how to fix it. You have to trust the person doing the work to blend the ideas.
My thought...Kevlar good on the inside doesn't sand well so it's good for an inner wet lay-up. Coremat I've used it for bulk and some stiffness no strength. Foam use boat build quality nothing else. Wood - never.

Good luck


Yes ,lots of good instructions! I discussed them today with the shipyard owner and have good news, mostly:

1) The foam aparently isn't a problem. One of his providers in Argentina has Divinycell and will ship truck (700 miles). Many thanks for all the sources indicated!

2) Realignment of the bow with the rest of the boat will be easier than I thought. The broken hull fell almost exactly in its normal place once turned upside down. Looks like the keel is ok.

3) He is familiar with the suggested techniques and says that his people can execute any of them. As you expected, he combined methods and added a few of ideas of his own.

We found a few other damages, all on the same bow, but not nearly as bad. Anyway, the current plan is the following:

1- Cut a rectangle from the center of the deck to below the end of the fupture on the inner float wall (the big rupture).

2- Use the opening made to inspect the inside and confirm or adjust the rest of the plan.

3- Patch the inside skin of the outer side of the float (smaller breakage), adding a longitudinal carbon batten between the two layers (windsurfer batten). He wants the battens to obtain more stiffness on the horizontal plane. On the vertical the keel and deck are far appart.

4- Laminate a one layer patch from the intact hull (waxed).

5- Remove the patch, clean the wax and laminate a second layer where the wax was, with two longitudinal carbon battens inserted between the two layers.

6- Clamp the battened patch to the rectangular hole.

7- Remove only the damaged foam and/or outside skin from the smaller rupture on the outer side of the float.

8-Glue new foam to the inner skins.

9- Sand, chamfer and clean the edges of the outer skin for the repair.

10- Laminate the outer skin (two layers), sand, coat and finish.

He'll do everything with epoxy/biaxial glass (but for the batttens). What do you think?
Cheers,
Posted By: Seeker

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/30/10 01:06 PM

The carbon battens and the fiberglass have differing strengths and modulus of elasticity...It is a case of divide and conquer...the carbon battens will be loaded up and take all the strain before the glass comes fully into play...after the battens fail you are just back to whatever glass cloth was used...it all has to work in unison and I am afraid the carbon battens and the fiberglass (more than likely E-glass) are too different in physical properties. That is something the windsurfing community found out back in the 80’s…it sounded good that the builders put a hybrid carbon cloth in the laminate, I saw one F2 board broken in half…they had a cloth with every 4th or 5th thread in “0” orientation was carbon fiber, the rest were E-glass. Others would add a few 1” carbon tows on a “0” axis along in the glass with the same failing results. Again…it is a case of divide and conquer. The carbon gets loaded up… fails, and what is left is just the glass…and because the builder was relying on the carbon as this miracle material, they used a lighter glass laminate…bam…catastrophic failure. There is more to adding carbon to a laminate than meets the eye..
Posted By: TheManShed

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/30/10 01:31 PM

Everything is good instead of battens form the same glass as used for the repair, less carbon, around a small diameter paper tube then cut it in half length wise. Use that instead of the batten
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/30/10 05:18 PM

Understood, in this type of repair one fiber type alone will work better than a mix of fibers. Many thanks to both of you!

I wonder if it makes sense to mold glass battens directly over the healthy hull, together with the patch lamination.

A question:

The inner skin will result stronger than the outer skin. I'd feel safer with the opposite. Considering that we'll have a relatively wide access to the inside, is it possible to patch the OUTER skin from the inside? (At least the big rupture?)

It would require the opening of a wider rectangle from the inside, by means of removing only the foam and inner skin to leave enough space for the patch under the outer skin repair.

The patch would be glued to the outer skin and then glassed from the outside to the right thickness. Afterwards, foam and inner skin would be glued to the inside. Or maybe the foam could be pre glued to the patch...

The other repair method would be used for the smaller rupture (or deck)

Cheers,
Posted By: Seeker

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/30/10 06:02 PM

I did something like that on a power boat to close up two large holes in the liner (8" X 32"). If the compound curve is not too extreme, use a piece of 1/32" gloss finish laminate (formica)cut oversize for a form .Taper everything well on the inside of the hull, then use contact cement to temp glue the Mica around the perimeter of the hole on the outside surface of the hull(or if the compound curve is too great take a mold off the good hull) and build up everything from the inside. After the repair you can break the bond of the contact cement with laquer thinner, wipe it clean with out a trace. Of course you have to have release wax where the actual repair lays against the form. Worked extremely well for me.
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 10/31/10 02:03 AM

Tom Haberman's reply to my request for advice essentially confirmed most of what was posted here. He also prefers the inner skin patch followed by the lamination of the same epoxy/glass/foam sandwich (vacuum bagged), so that is the way we will try. Thanks guys!
I will do my best to photograph and post the repair progress.

Mr. Haberman was surprised that the composite did not show signs of weakening and failed without warning, but he didn't see the pictures from before the re-coat job. The weakening was visible, I saw it and just failed to act accordingly. My only excuses are that I didn't know Supercat 15 hulls were glass/foam composite and that I trusted the advice of a shipyard owner who, in turn, has no experience with composites and also did not know the hull was composite.

Besides, I might have understated how hard we were sailing the boat. The total crew weight was over 200 kg (over 440 lb) and the wind was blowing about 30 knots, with stronger irregular gusts, as is common in small inland lakes.

The pitchpole was preceded by three or four bow buries and happened on our way to the finish line, while pushing the boat hard to recover from a couple of horrible tacks that had cost us the first place. It was the first time on a beach cat for the crew (the shipyard owner). The finish line was in front of the club instead of downwind.

(digression: we do this when there are spectators like press or sponsors, so they can see the finish and take pictures. You don't want them in the water when it is blowing. end of digression)

So, we would point higher in the lulls and bear away in the gusts. Worked fine until a stronger gust caught us in the famous death zone. An older SC15 competitor said that I should have dumped, pinched and capsized, as he did. It cost him the race just like ours, but the capsize did not cause any damage at all.

Cheers,
Posted By: Hellkell001

Re: Advice on fixing a nearly chopped Supercat 15 bow - 02/17/11 07:53 PM

So what is the latest with the repairs?
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 02/18/11 07:32 PM

Originally Posted by Hellkell001
So what is the latest with the repairs?


This is a spare time job for the shipyard and the owner has to supervise it personally. Also, I want to be present during the critical parts.

We waited a lot for the epoxy and pvc foam, barely started with the repair and then I travelled. When I returned the shipyard owner travelled. Work will resume when he comes back.

I'll keep the thread updated.
Thanks for the interest!
Posted By: Luiz

Re: Advice on fixing a nearly chopped Supercat 15 bow - 05/25/11 01:06 AM

Originally Posted by Luiz
I'll keep the thread updated.


After almost five months in the shipyard and one month waiting for me to rig it, the SC15 was officially re-launched last sunday. The glass/foam/gelcoat job looks impecable, with a mirror-like finish. My daughter had to ask what side broke for she couldn't find it simply looking and feeling.

Unfortunately I have no pictures. The last months were very busy and I could only visit the boat twice and didn't have a camera with me.

Still, AFAIK it was fixed using the drawings I made based on the instructions and techniques received here and from Tom Haberman - many thanks to all of you!

I tried to post the drawing and instructions here but (for obvious reasons) they are in Spanish and the max size makes the image fuzzy. Anyway, it gives an idea of what to do and anyone interested can get the uncompressed file from me.



Attached picture detalle reparacion casco sandwich-pequeno.jpg
Posted By: TheManShed

Re: Advice on fixing a nearly chopped Supercat 15 bow - 05/25/11 01:58 PM

Very Cool!
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