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1/10 of a knot

Posted By: pgp

1/10 of a knot - 05/04/11 11:45 AM

What would it take to improve my boat speed by that much?

Take into consideration my boat is five years old. A reduced pork chop diet is out of the question!
Posted By: Cab

Re: 1/10 of a knot - 05/04/11 11:50 AM

Fill the dings/scratches that are on the bottom of all our boats and wax it a few times.
Posted By: pgp

Re: 1/10 of a knot - 05/04/11 12:01 PM

I'm not so sure about the wax. But, is it really that easy to pick up 1/10?
Posted By: Timbo

Re: 1/10 of a knot - 05/04/11 12:20 PM

Why are you not so sure about the wax?

No fan of simple physics?

Go get Frank Bethwaite's book, High Performance Sailing. In it he lays out exactly what a dirty hull will cost you in speed, and it's a lot more than 1/10th of a knot.

http://www.amazon.com/High-Performa...mp;s=books&qid=1304511678&sr=1-1

Read some of the reviews...if you race sailboats but don't own this book, well, it would be money well spent.
Posted By: pgp

Re: 1/10 of a knot - 05/04/11 12:37 PM

Way back when, I'd heard that since wax is soft any scratches in the wax itself are as bad as scratches to the boat.

I'll get the book. But in the mean time, if a clean fair hull is ultra important, what would you go to get it? Wet sand with 1000 grit then buff with rubbing compound seems like over kill though it looks nice.
Posted By: Timbo

Re: 1/10 of a knot - 05/04/11 12:46 PM

Don't use soft wax, use Teflon. McLube makes the right stuff. http://www.mclubemarine.com/

But first I would take it to a professional racing boat shop and have them board sand it and re-gelcoat it. You don't want to do it by hand wtih a small block, it won't be fair enough. You need a longboard, and it's a "job".
Posted By: Karl_Brogger

Re: 1/10 of a knot - 05/04/11 12:58 PM

Put your pork chop laden weight where it belongs..... laugh
Posted By: pgp

Re: 1/10 of a knot - 05/04/11 01:09 PM

Good morning sunshine!

So, what's your take on a fair hull? When does it become overkill?
Posted By: jkkartz1

Re: 1/10 of a knot - 05/04/11 01:16 PM

There is a boat shop out on 771 near Port Charlotte's Gardens of Gulf Cove owned by a Russian? that does fairing for the Olympic Stars and other race boats. I was driving home from Englewood and saw a truck from Michigan pulling a Star with the best looking fiberglass I have ever seen

Probably expensive.
Posted By: Timbo

Re: 1/10 of a knot - 05/04/11 01:33 PM

If you can't eat off the bottom, it's too dirty. I wash and wax my boat (and daggers and rudders) the day before I go to a regatta, then wash the hulls again when I arrive at the regatta, before I take it off the trailer.

Road grime picked up while trailering to the regatta is slow. In the book mentioned above Frank did drag tests of hulls that had been washed after trailering and not, it was very clear which were always faster.

Shall we talk about the dirt on the mast and sails now? Anyone know of a good aluminium polish? ;^)
Posted By: pgp

Re: 1/10 of a knot - 05/04/11 01:46 PM

"...aluminium polish?" laugh I was thinking the same thing but not very seriously.

My boat is well past time for a good overhaul and I was wondering just how far to go. It is still a beach cat and the best finish in the world probably wouldn't survive the first launch/landing or even sand on the trailer cradles.

Posted By: Timbo

Re: 1/10 of a knot - 05/04/11 02:09 PM

You don't 'drive it on' to the beach do you?

Yeah, that will -undo- all the board sanding, gelcoat and wax!

I stop in a foot of water and go get the wheels.
Posted By: mikeborden

Re: 1/10 of a knot - 05/04/11 02:37 PM

There has been and always will be an argument for waxing or not waxing the boat because of boat speed.

My argument....
It keeps the nasty grim off and I don't have to wash it as often.

A sexy boat is a clean boat, which in turn looks fast!

Mike
Posted By: pgp

Re: 1/10 of a knot - 05/04/11 02:46 PM

"...go get the wheels." That's fine when I have crew but a problem when I'm uni. Lately, I've had a mooring line to return to and that is very nice.

Mike: what kind of wax do you use?

Posted By: mikeborden

Re: 1/10 of a knot - 05/04/11 02:57 PM

I use the Mcguires cleaner wax from the local O'reily's. It waxes and it clean some stuff off of the hull. I also use that on my spin pole.

I have used the Holmekol and it's very nice, just a little expensive. smile

What I generally do is at the beginning of the year, I use the Holmekol for the "base" if you want to call it that, and the rest of the year use the McGuires.



Posted By: tback

Re: 1/10 of a knot - 05/04/11 03:40 PM

Originally Posted by pgp
"...go get the wheels." That's fine when I have crew but a problem when I'm uni.



Pete, when I sail uni i have a small anchor that I tie a line to with a milk jug as a buoy. After launhing the boat, I drop the anchor and tie off my wheels to it right out in the water. When I finish sailing I come in and sail right to my wheels.

BTW, sometimes you need to raise your sails on the water, if so, then you can tie off to the makeshift mooring buoy to do that.
Posted By: Anonymous

Re: 1/10 of a knot - 05/04/11 03:46 PM

Originally Posted by pgp
Lately, I've had a mooring line to return to and that is very nice.

With you on that. In case anyone is interested, I've found this to be a great help.
Posted By: Rolf_Nilsen

Re: 1/10 of a knot - 05/04/11 03:59 PM

1/10th of a knot out of your boat? Easy.. smile

Sail more, and get some qualified, honest, feedback on your sailing and what to improve.

Probably not the answer you wanted.
Posted By: pgp

Re: 1/10 of a knot - 05/04/11 04:43 PM

I hear you Rolf. wink

For some reason, I find it is actually easier to raise and lower the main when the boat is on the water.
Posted By: Karl_Brogger

Re: 1/10 of a knot - 05/04/11 06:08 PM

Originally Posted by pgp
Good morning sunshine!

So, what's your take on a fair hull? When does it become overkill?


I don't own boats long enough to scratch them any more. I'm with mike though, I just want it easy to clean and keep the brown stains at bay, (I should wax my underwear lol) I actually use the same exact wax. Smoother and straighter will be faster, that I do know. But as far as wax or not I couldn't tell you if it makes a difference.
Posted By: taipanfc

Re: 1/10 of a knot - 05/05/11 03:27 AM

Very important to have faired hulls/foils. At the moth worlds the top guys were wet sanding their foils with 1200 every morning before racing. Because the foil is the only bit in the water, and due to the high speeds, any scratch can be felt through less than smooth ride and increased rooster tail off the foil which means lower speed.

On a cat with a long w/line length, there is a lot of turbulence so you don't feel these imperfections as much, but they are still there. So get out there and make sure the hull/foils are smooth! (Plus the boat looks better too)
Posted By: Brian P

Re: 1/10 of a knot - 05/05/11 05:23 AM

of course all this extra sanding fairing polishing waxing is all undone with one stuffed tack, or a bad start. so until you can get all the way round the course without blowing a single tack or a mark rounding. whats more beneficial?? 100 hours in the "man-cave" or 100 hours extra time on the water practising? and please? polishing the mast?? if you polish your mast are you also removing all fittings from the deck or placing wind deflectors in front of every fitting, cos i think you will find thewy will cause a lot more wind disturbance than a mast that isnt mirror polished. next you will see guys racing their cats in cycling outfits with pointy back helmets!!! hahahaha
Posted By: Brian P

Re: 1/10 of a knot - 05/05/11 05:28 AM

dont get me wrong, i understand the need for a smooth hull, and 1200 sanding before everyrace, yeah if your in contention for world champs maybe. and i also know that all the 0.1%'s all add up, what i am saying is make sure you have all your 5%'s out of the way first. and good luck to anyone who wants to put the effort in to polishing hulls, ill drop my boat off to your place and you can practice on mine first. if its easier you can do my boat at my place, there is beer in the fridge in the " man cave", help yourself!!!!
Posted By: pgp

Re: 1/10 of a knot - 05/05/11 10:33 AM

The finish on my boat is getting pretty bad after 5 years and I must do something. Seems wet sanding with 1000 grit is all that's necessary.

Polishing the mast was a joke.

However, vmg is no joke. [see new thread]
Posted By: sail7seas

Re: 1/10 of a knot - 05/05/11 01:11 PM

>of course all this extra sanding fairing polishing waxing is all undone with one stuffed tack<
What about the start?
If the boats around you have a 1/10kn, you will be eventually blanketed or backwinded, and pushed way back in the fleet?
You could tack out of this situation, if that is the way to go, or just be patient and get more bad air?
Posted By: Timbo

Re: 1/10 of a knot - 05/05/11 01:13 PM

Pete, you may want to bring your boat by that shop Jack mentioned above and ask them what they recommend, they could tell you exactly what and how to do it...correctly, might save you some time and effort, maybe get a price for them to do it for you too.

I have a good friend who does a lot of fiberglass work on airplanes, that's who I take my boards and hulls to whenever I put dings in them. He does great work but I do have to pay him. If you want me to I'll ask him about a price to re-gelcoat your hulls.
Posted By: mini

Re: 1/10 of a knot - 05/05/11 02:33 PM

There is "Pride in your ride". A nice shiny boat looks good and can make you feel good.

As far as gaining 1/10th of a knot – BS. Maybe in theory if you are already sailing it to its maximum.
If you are over steering, pinching, sheeting poorly or any number of the other 1000 things you can do wrong to go slow then those same things affect both the boat speed and the potential you might have gained by having a beautifully polished hull bottom.
Of those performance related driver techniques, maybe your are 50%, now you have 1/20th of a knot available form a whole lot of expense and effort.

You can gain 2 knots just from practice and it is a whole lot more fun than wet sanding.
Posted By: pgp

Re: 1/10 of a knot - 05/05/11 03:37 PM

I understand your point. I'm trying to do both, put more time on the water and have a well prepared boat.

The 1/10 seems, imo, a useful increment to determine where to spend time and money off the water.

Bottom work seems the quickest, easiest way to pick up speed and is most likely to be needed. My boards also need work, they are nicked and gouged. To my mind, the two jobs are very similar and can be accomplished at the same time.

Posted By: Rolf_Nilsen

Re: 1/10 of a knot - 05/05/11 05:52 PM

What can save massive amounts of time on the racing course is not having stuff breaking! Make sure all your lines, fittings etc is top notch before you begin to polish your hull! Better to invest in general maintenance if you have time available in the "man cave"

Polishing the foils is OK.
Posted By: Timbo

Re: 1/10 of a knot - 05/05/11 07:26 PM

Rolf, that is exactly why I force myself to wash my boat before a regatta. I always find...something...that needs to be replaced, tightened, fixed or what ever, every time I wash it. It's not 1/10th of a knot of speed I'm worried about finding, it's all the little things that can stop you dead! A great way to get a good look at them is by washing the boat.
Posted By: Smiths_Cat

Re: 1/10 of a knot - 05/06/11 07:07 AM

If you stroke with your hand over the hull and it feels smooth it is okay. Scratches along the hull are less worse than others. Scratches are more worse in the forward part than in the aft part of the boat.
Foils should be fairly smooth. 800 or 1000 sanding paper required.
I do this ones per year. Wax is a must on gelcoat boats. Canuba is the best, forget all the other stuff, it is the same just more expensive.

Cheers,

Klaus
Posted By: MitchB

Re: 1/10 of a knot - 05/06/11 02:12 PM

After 5 years.... After ~25 years the creases in my hull, rips in the paint, chunks missing from the bow are probably starting to slow me down!

I often think to myself that I should fair it and re paint or have it done. But I would much rather just get out there and sail!!! If I can't pick up 1/10th after a few days on the water then I'm going backwards!
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