Robi,

1. Ouch!........ugly for sure!...........but not that bad of a fix.

2. We would just repair it,...like you said, part of the fun. Heck, when you travel to regattas, 'bites' like that are common,..and you have to fix them on the beach that night,....so to be ready to race the next morning.

3. However, ..if the builder is a truck ride away,...by all means go there,.....it will be a perfect job..

4. Why did you not dissassemble the hulls and pull them in your living room?......you pull everything else in there..:-) ,.......heck, you could rest your feet up on them as you watch TV...


Bruce
I-17
St. Croix ( by way of Tampa)

I have to respectfully disagree with this recommendation. There is no compatibality issue between epoxy and CURED polyester or vinylester resins. The Cte between the three is close enough to be inconsequential. The most important property for a repair resin is adhesion and epoxies have unquestionably superior adhesion to the other two types for at least two reasons: 1) uncured epoxy resin hass far lower surface tension (it is 'wetter', like comparing soapy water to pure water)and 2)epoxies are solvent-free resin systems. Vinyl and polyester resins both depend on the solvent styrene(vinylbenzene) to reduuce viscosity to a usable level. This is a 'reactive' solvent which means some of it becomes part of the cured resin. But not all of it does so. The part that does not evaporates shortly after the resin transitions to a solid. The loss of this free solvent ALWAYS results in significant shrinkage of the cured mass thus reducing adhesion further. Look at the shrinkage numbers for epoxies vs vinyl/polyesters and you will see something like 10X more shrinkage compared to epoxy.

Shrinkage is not necessarily a bad thing in production; it helps de-mold the part. The lighter viscosity, faster processing times and cheaper price for vinyl/polyester makes them the right choice in production,especially since the advent of resin infusion.

But repairing and manufacturing are definitely different games.

For repairs 'stick' with epoxy

Jimbo

I agree and typically use epoxy for repairing any composite structure. However, if you choose to finish the repair with gelcoat, you may have an issue getting it to adhere well to the epoxy.

Hi

I have to vehemently disagree with Jimbo's suggestion of using aluminum as the backing plate.

Use a piece of 1/32" (.031") thick G10/FR4 (this is a fiberglass-epoxy composite already cured). The aluminum will rot away (unless it is anodized first), very tricky to get a good bond, and is twice as heavy and stiff as the G10 - which more closely matches the resin/cloth your boat is built with.

For 1/32" G10 go to McMaster.com PN:8667K111 (6" x 6" for $2) or 8667K51 (12" x 12" for $3.95).

Otherwise all the other advice seems correct.

Also, a great source for quality cloth is: www.uscomposites.com. I highly recommend using the 4 oz 6oz S-glass.

I've done over 100 fiberglass repairs on foam cored boats, etc. E-mail me directly if you need more info.

Steven Bellavia
Hobie FX-1, Sail # 211

The idea is to let it rot off. It's only there as a temporary back up plate to facilitate the repair. That way everything can be done from the front side. But G10 should work fine, too. G10 is circuit board fiberglass, for those unfamiliar. It is readily available in many different thicknesses. I get G10 from MSC supply.

I've only done maybe 20 repairs to sandwich core boats, myself. I have done hundreds of radomes, floors, flaps and ailerons, though, with every type of construction from metal over balsa, glass/carbon/kevlar over nomex h'comb or various foams to metal skins over metal honeycomb.

Jimbo

Why would you make a repair with epoxy when the original lay-up is in vynalester resin and polyester gel coat???
For maximum compatibility and "as new" finish you always use the same materials as the original. If you had an aluminium fitting that was fractured and you had to "repair" it instead of replace it, would you fasten a stainless steel piece to it because the stainless is stronger? I think not as the risk of acute electrolysis would soon create a worse failure (although I've seen people do this with disastrous results) Complete compatibility between original materials and "repair" materials is always the most logical and best method of any maintenance.

So vinyl ester construction with an epoxy repair will be vulnerable to electrolysis Daryl? Not sure comparing resin repairs to galvanic corrosion is really relevant...

Epoxy will shrink less and has more cross-linking adhesive bonds than vinyl ester. That said, I'm sure a competent person can turn out a good repair in either material.

How on earth do you equate my previous post to something as far out as, epoxy with vynalester will be vulnerable to galvanic corrosion??? (I assume that it was a "flippant", throw away remark and take it as such) The point was that it is always better to make repairs with the same materials that were used in the original laminate layup when it comes to "fibreglass" repairs and that there is a, not insignificant, problem when finishing off the repair "to original" condition when polyester gel coat has to be applied over freshly set epoxy. It is a situation that no professional boat builder or repairer would put themselves in, and if you think differently simply ask one.

errr... you used a comparison to repairing aluminum with stainless and suffering electrolysis (galvanic corrosion) to make some kind of point about not using epoxy to repair a vinyl ester construction hull. My flippancy was a polite way of highlighting your comparison was bull. As is your statement that using the same materials as original construction is always "logical".

I thought you could put gel coat over epoxy repairs if you remove the amine blush? Not that you'd want to thought - Awlgrip paint or similar can be simpler and quicker than using gel coat - as a professional boat builder and repairer once told me...

It's obvious that what you don't know about boat building and boat repairs would fill ten thousand volumes Flump, and what you think that you do know is dangerous advice for unsuspecting others. Your manners are in a similar state I'm sorry to say.

Darryl,

Which bit of my advice is dangerous?

You seem a little touchy on-line at the moment - perhaps it was your roasting on Sailing Anarchy?

Nahh, just a slow day with not enough to do and it hasn't stopped raining for two days.

Hi Robi,
I saw you were registered for Gilligan's Run, are you still going. One solution would be to stop at Vector on the way up and have them do a fix on it and drop it off on the way back home to have them make it look pretty.

It was great meeting you at the Delray and was looking forward to sailing against you this weekend on your new sled.

Woaaahh Darryl...chill - sam's not in on this thread yet. What the flump is saying is well documented. Epoxy adheres better to cured ester resins that ester resins but ester resins adhere to epoxy even less. In this case, I agree that the difference is negligable as it applies to the repair area and that if gel coat will be the end finish method that the same vinylester or polyester resin should be used.

GALVANIC CORROSION THINGY....................To get that nasty piece of aluminum plate out of the hull. 1. Tie a piece of string to the plate. 2. Lead the string through down through the hull and out the drain hole. 3. Tie the other end to your front door knob. 4. have your wife distract the Blade 001 by saying, "Hey look at the A-Cat. 5.When it looks ! Slam the door ! Thats good idea CyberSpeed had Robi.....

Nah cant make it out. I prefer to sail the boat intact than with masking tape. Dunno its just the way I am. Thanks for the invite though.

Awesome door idea BTW!!

Talked to a local beachcat guru, we are going to repair it. Should be done in the next couple of weeks.

Yeah, Sorry abgout that Flump, I have been sitting in my office staring out at grey wet drizzling skies for weeks now and I am sick of it ( its downright un Australian, we can handle droughts without a blink but continual wet !!!) on top of that its freezing ! the temperature got down to 12 degrees C yesterday and I had to got and pee every ten minutes it was that cold (don't know how you guys can stand a northern winter) even the water temp' is down to about 17C which make an important part of your anatomy receed into your stomach - just not a good time for a sailor.