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Author Topic:   Loss of speed with bottom paint

Over the LINE posted 03-21-2003 03:09 PM ET (US)
Does anyone have any real world numbers on how much speed bottom paint robs. I am considering removing the paint from my 13' (I know about the mess or expense, depending on if I do it myself or pay someone else) but don't know how much speed it is worth. Numbers from any kind of boat would be appreciated because they can be coverted into a good average percentage.
Thanks Chris
Bigshot posted 03-21-2003 04:16 PM ET (US)
I have owned both a 13 with paint and without. No real numbers but I doubt it meant 1mph.
captbone posted 03-21-2003 08:38 PM ET (US)
The smaller the boat the less the gain. A good hard sanding with new paint will get you close to no bottom paint speed.
Sal DiMercurio posted 03-21-2003 08:58 PM ET (US)
I painted my bottom last year, no loss at all.
Myself & buddy Dunk from the wmi site feel it allows more air over the surface of the bottom, & it gives a rippled surface compared to a flat smooth surface.
We used to pain the bottom of my 21 ft flat bottom race boat [ custom built ] with a hair under full load hemi 6 strombergs, un-blown, with graphite paint.
We did get better speed with the painted, compared to a waxed bottom.
Sal
captbone posted 03-21-2003 09:23 PM ET (US)
I think that older bottom paint is where you loss your speed. After a few years, it will chip and have small ditches in it, and a surface that is not true. Over 10 years of bottom paint is thicker than most think.
Over the LINE posted 03-21-2003 09:45 PM ET (US)
I'm a racing sailor with both trailer sailed (no bottom paint) and slip kept boats. It never occured to me that the paint would have minimal effect. I am so fanatical about wet sanding and teflon wax that I just naturally went the same way with the 13'. Maybe a little sanding will make me feel better about this bottom.
Sal DiMercurio posted 03-22-2003 12:49 AM ET (US)
You get your best speeds on a 12" to 18" chop [ following sea ], I don't believe bottom paint is going to slow you down with 90% of the boat riding on air.
Sal
BugsyG posted 03-22-2003 08:03 AM ET (US)
Does it have anything to do with the fact that if there is water in the hull, and engine size? Could the bottom kind of "throw-off" the bottom so that it slows it down a lot? Thats a good question.
JAZZ
Over the LINE posted 03-22-2003 07:44 PM ET (US)
Most of my time is spent running the Louisiana marsh. Not a lot of chop. But I agree that if the hull is not in the water paint has little if any effect.
As far as water in the hull or engine size, I am almost positive there is no water in the hull, but am going to weigh it Sun or Mon just because. I am running a brand new Yamaha 50 (just finished break in an hour ago) so I haver plenty of power.
I am actually still prop tuning so I don't have a true top speed yet. I don't think I am slow, but was wondering what I might gain by removing the bottom paint.
Sal DiMercurio posted 03-22-2003 10:11 PM ET (US)
If your going to put the boat in the water for an amount of time, you better leave the pain on.
With a little 13 with a new 50 hp, I really feel the paint wont effect it at all.
Just prop that engine so she reaches maximum recommended rpms, thats far more important then worrying about the painted bottom.
If you so set on getting more speed, why didn't you get a bigger engine?
I would think a 50 hp on that boat is about as much as that boat can handle, as she's gonna get pretty squirilly as it is.
Sal
Over the LINE posted 03-22-2003 11:15 PM ET (US)
You're right, she is a little squirley with the 50, if I'm by myself. Most of the time I use the boat well loaded so the 50 is just right. I've ridden a 13' with a 60 and knew I did not want to go that far. I am a tweaker by nature and just trying to get everything from the boat that it has to give.
The boat stays in the water Friday afternoon until Sunday afternoon, in brackish water, for duck season (two months). Beyond that it stays on the trailer except for the occasional day. I don't really need bottom paint, but it was on the boat when I bought it.
Thanks for all the input.
Chris
flaglerdave posted 03-23-2003 06:04 AM ET (US)
My 2 cents..
If you leave the whaler in the water with out a bottm paint, the growth will slow down the hull as well.
Bigshot posted 03-23-2003 10:31 AM ET (US)
How high is the engine? If you are running in shallows etc, the best bang for your buck will be a manual jackplate which will make a BIG difference.
Over the LINE posted 03-23-2003 11:06 AM ET (US)
The boat is not going to stay in the water long enough to have any real buildup, so I am not really concerned about that.
I already went for the jackplate. (Some of the places I go are really shallow, a foot or so.) I have not really pushed the height yet, but will as soon as I am close on the prop. I am going to exchange for prop number four tomorrow.
Thanks-Chris
baybug posted 03-24-2003 08:35 AM ET (US)
Sand and paint with VC 17. You'll increase your top end.
mustang7nh posted 03-25-2003 08:03 AM ET (US)
What is VC17?
I'm in the process of manually scraping 14 years of bottom paint off. It is actually coming off pretty easy, last years bald spots that now have fresh paint adhered directly to the gel coat are actually alot harder. HOwever, you still have that residue after scraping it bare. Any thoughts on how to take that last bit off? I am going to repaint it, so do I need to bother? Thanks
Bigshot posted 03-25-2003 08:56 AM ET (US)
Don't bother with residue. Wet sanding it will take it off if you decide not to repaint.
baybug posted 03-25-2003 09:10 AM ET (US)
VC 17m is a Teflon Copperoxide paint made by Interlux. A lot of sailboats (almost all racing boats that are kept in the water) use it as well as power boats in the Great Lakes area. Great stuff. They also have "VC Offshore" for saltwater. I have had it on my Hunter, Outrage and Edgewater.
http://www.yachtpaint.com/usa/

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Author	Topic: Loss of speed with bottom paint
Over the LINE	posted 03-21-2003 03:09 PM ET (US) Does anyone have any real world numbers on how much speed bottom paint robs. I am considering removing the paint from my 13' (I know about the mess or expense, depending on if I do it myself or pay someone else) but don't know how much speed it is worth. Numbers from any kind of boat would be appreciated because they can be coverted into a good average percentage. Thanks Chris
Bigshot	posted 03-21-2003 04:16 PM ET (US) I have owned both a 13 with paint and without. No real numbers but I doubt it meant 1mph.
captbone	posted 03-21-2003 08:38 PM ET (US) The smaller the boat the less the gain. A good hard sanding with new paint will get you close to no bottom paint speed.
Sal DiMercurio	posted 03-21-2003 08:58 PM ET (US) I painted my bottom last year, no loss at all. Myself & buddy Dunk from the wmi site feel it allows more air over the surface of the bottom, & it gives a rippled surface compared to a flat smooth surface. We used to pain the bottom of my 21 ft flat bottom race boat [ custom built ] with a hair under full load hemi 6 strombergs, un-blown, with graphite paint. We did get better speed with the painted, compared to a waxed bottom. Sal
captbone	posted 03-21-2003 09:23 PM ET (US) I think that older bottom paint is where you loss your speed. After a few years, it will chip and have small ditches in it, and a surface that is not true. Over 10 years of bottom paint is thicker than most think.
Over the LINE	posted 03-21-2003 09:45 PM ET (US) I'm a racing sailor with both trailer sailed (no bottom paint) and slip kept boats. It never occured to me that the paint would have minimal effect. I am so fanatical about wet sanding and teflon wax that I just naturally went the same way with the 13'. Maybe a little sanding will make me feel better about this bottom.
Sal DiMercurio	posted 03-22-2003 12:49 AM ET (US) You get your best speeds on a 12" to 18" chop [ following sea ], I don't believe bottom paint is going to slow you down with 90% of the boat riding on air. Sal
BugsyG	posted 03-22-2003 08:03 AM ET (US) Does it have anything to do with the fact that if there is water in the hull, and engine size? Could the bottom kind of "throw-off" the bottom so that it slows it down a lot? Thats a good question. JAZZ
Over the LINE	posted 03-22-2003 07:44 PM ET (US) Most of my time is spent running the Louisiana marsh. Not a lot of chop. But I agree that if the hull is not in the water paint has little if any effect. As far as water in the hull or engine size, I am almost positive there is no water in the hull, but am going to weigh it Sun or Mon just because. I am running a brand new Yamaha 50 (just finished break in an hour ago) so I haver plenty of power. I am actually still prop tuning so I don't have a true top speed yet. I don't think I am slow, but was wondering what I might gain by removing the bottom paint.
Sal DiMercurio	posted 03-22-2003 10:11 PM ET (US) If your going to put the boat in the water for an amount of time, you better leave the pain on. With a little 13 with a new 50 hp, I really feel the paint wont effect it at all. Just prop that engine so she reaches maximum recommended rpms, thats far more important then worrying about the painted bottom. If you so set on getting more speed, why didn't you get a bigger engine? I would think a 50 hp on that boat is about as much as that boat can handle, as she's gonna get pretty squirilly as it is. Sal
Over the LINE	posted 03-22-2003 11:15 PM ET (US) You're right, she is a little squirley with the 50, if I'm by myself. Most of the time I use the boat well loaded so the 50 is just right. I've ridden a 13' with a 60 and knew I did not want to go that far. I am a tweaker by nature and just trying to get everything from the boat that it has to give. The boat stays in the water Friday afternoon until Sunday afternoon, in brackish water, for duck season (two months). Beyond that it stays on the trailer except for the occasional day. I don't really need bottom paint, but it was on the boat when I bought it. Thanks for all the input. Chris
flaglerdave	posted 03-23-2003 06:04 AM ET (US) My 2 cents.. If you leave the whaler in the water with out a bottm paint, the growth will slow down the hull as well.
Bigshot	posted 03-23-2003 10:31 AM ET (US) How high is the engine? If you are running in shallows etc, the best bang for your buck will be a manual jackplate which will make a BIG difference.
Over the LINE	posted 03-23-2003 11:06 AM ET (US) The boat is not going to stay in the water long enough to have any real buildup, so I am not really concerned about that. I already went for the jackplate. (Some of the places I go are really shallow, a foot or so.) I have not really pushed the height yet, but will as soon as I am close on the prop. I am going to exchange for prop number four tomorrow. Thanks-Chris
baybug	posted 03-24-2003 08:35 AM ET (US) Sand and paint with VC 17. You'll increase your top end.
mustang7nh	posted 03-25-2003 08:03 AM ET (US) What is VC17? I'm in the process of manually scraping 14 years of bottom paint off. It is actually coming off pretty easy, last years bald spots that now have fresh paint adhered directly to the gel coat are actually alot harder. HOwever, you still have that residue after scraping it bare. Any thoughts on how to take that last bit off? I am going to repaint it, so do I need to bother? Thanks
Bigshot	posted 03-25-2003 08:56 AM ET (US) Don't bother with residue. Wet sanding it will take it off if you decide not to repaint.
baybug	posted 03-25-2003 09:10 AM ET (US) VC 17m is a Teflon Copperoxide paint made by Interlux. A lot of sailboats (almost all racing boats that are kept in the water) use it as well as power boats in the Great Lakes area. Great stuff. They also have "VC Offshore" for saltwater. I have had it on my Hunter, Outrage and Edgewater. http://www.yachtpaint.com/usa/