Need For Speed

[umblecumbuz]

Re: Need For Speed

In a go faster boat, your bottom gets sore enough without sanding it!

 

[garycinn]

Re: Need For Speed

Coming from a sailing/racing world, where the tagline is "Man invented the slowest form of transportation and then decided to race it."<br /><br />It is VERY common to sand hulls vs. wax.<br /><br />Some reading:<br /><br /> http://old.cruisingworld.com/grimes.htm <br /><br /> http://www.thebeachcats.com/OnTheWire/www.catsail.com/archives/v3-i2/feature4.htm <br /><br />IMO, at the end of the day it is minutia. Wax it and make it look pretty and you feel good .

 

[one more cast]

Re: Need For Speed

Some where a long time ago I seen where racing boats actually put little humps or scoops on the bottoms of there boats to make air bubbles to reduce friction. Also a small sea plane is harder to get lift off on a flat lake verses a wavy lake because the waves give air space and reduces friction.

 

[lakelivin]

Re: Need For Speed

garycinn,<br /><br />thanks for the references but now I think I have a headache. Will have to reread when I'm a bit sharper. but one thing that did register (I think) is that when they talk about sanding, they're talking about wet sanding with very fine grit sandpaper, which would seem to make the surface very smooth, not rough.

 

[waterone1@aol.com]

Re: Need For Speed

Garycinn, I just read the links you provided, and unless I am drunk, it very clearly is making the case for a smooth hull. And as Lakelivin said, they are talking about finish sanding...to get the hull as smooth as possible.<br />I was on the Interlux website today (company that makes bottom paint) and they also were talking about how some of their bottom paints (applied with a roller) can be sanded after application to make them smoother, for speed boats.

 

[Bob_VT]

Re: Need For Speed

If you "prepare" the hull weather it be with wax, sanding, drilling holes... it will only have a slight effect on speed. As soon as you add a person to the boat you will loose the edge you gained by the added weight! (I had sanded a hull I had and only gained 1.5 mph by gps over the waxed hull. Been there - done that!)<br /><br />A stainless prop always improves performance versus aluminum.<br /><br />Try this experiment... get in your car and set the cruise on 60 mph drive for a few minutes and then set the cruise on 62 mph. There is a slight differance but not percieved as speed!<br /><br />Evaluate your needs. If you really have the desire for speed buy a second boat that is designed for high performance.<br /><br />Bob

 

[umblecumbuz]

Re: Need For Speed

Bob<br /><br />If you could show the speed boys a 1.5 mph gain, they'd be all over you!<br /><br />That's not a 'slight' difference - that's a million-mile difference!<br /><br />Better get rid of the wax on my hull.<br /><br />Ciao

 

[lakelivin]

Re: Need For Speed

Ignoring the wet sanding for a moment, seems to me if you were going to put a finish on your hull a polymer type might be better than wax. <br /><br />I get the impression that wax would leave a thicker, probably 'rougher' coating. <br /><br />From the Zaino show car finish site:<br />"The emulsion allows our polish to spread so thin, so evenly, that the resulting finish is nearly flat and very, very smooth. Simple, really, our polymer strands are exceptionally long, creating a very high surface bond with your paint for lasting protection. Plus, our special polymer formula creates chains that cross-link rapidly, allowing the polish to fill and level the micro-valleys in your car’s paint to produce an ultra-flat surface."<br /><br />Not pushing that particular brand, just first place I found with info that might explain my hunch.<br /><br />Thoughts?

 

[mattttt25]

Re: Need For Speed

here's what a friend explained to me. he's big in the go-fast crowd:<br /><br />A waxed hull is said by some to be slower, but easier to clean. When you here about a sanded hull, they mean ROUGH sanded. The idea is to create turbulence at the hull/water interface which should loosen up the hull. This is similar to the idea of a step. PWC racers sand the hulls since they don't have steps. Race boats have tried sanding but it is not as effective, likely due to the size of the hull and weight of the boat. If you go with this theory then it would explain why a waxed hull is slower-less turbulence would mean more hull/water interference.<br /><br />When a hull is blueprinted it is usually made perfectly straight. Any hook or rocker put in by the manufacturer is removed and the bottom is trued side to side. This will make the hull faster but in some cases expose deficiencies that the manufacturer was covering up a hook or rocker during the mold process. <br /><br />None of these things will make a noticeable difference in a recreational boat. You might need to spend 100 hours on a hull to get 1 mph on the top end.

 

[lakelivin]

Re: Need For Speed

mattt, your rough sand friend seems to be in the powerboat crowd, the smooth sand articles are both from sailboaters. <br /><br />Wonder if the difference in speeds might have something to do with physics behind the differing recommendations. Or perhaps the difference between speed boat hull designs and sailboat hull designs. Or if this is another 'oil' topic that will generate debate forever.

 

[mattttt25]

Re: Need For Speed

i think you're touching on it. i have to assume there's a big difference is maximizing hull efficiencies in displacement and planing hulls. two different animals.

 

[cuzner]

Re: Need For Speed

Some new performace boats have a V shaped wedge moulded into bottom of the boat.theory is add air between hull and water= reduced friction, more speed, and better economy. Don't know how good it works but it does look good.<br /><br /> Jim

 

[scott begovich]

Re: Need For Speed

When a hull is blueprinted it is usually made perfectly straight. Any hook or rocker put in by the manufacturer is removed and the bottom is trued side to side. This will make the hull faster but in some cases expose deficiencies that the manufacturer was covering up a hook or rocker during the mold process. <br /><br />None of these things will make a noticeable difference in a recreational boat. You might need to spend 100 hours on a hull to get 1 mph on the top end.

An excellent assesment in my opinion. As an offshore Racer who has won a fair share of races, I can tell you that blueprinting a hull can (in my experience creat a 5-6mph gain)<br />With the boat in question, you are right, the gain may not be a great, You could try to take the hook out of it wich should give you an increase but may suffer in low end performance such as getting out of the hole. If speed is something very important to you, than by a hull built for it.<br />Speed is great, but can get extremely expensive and dangerous.<br />Scott Begovich<br />Owner/Driver Kean University Offshore<br />2004 Key West World Champions

 

[mattttt25]

Re: Need For Speed

cuzner- you are referring to a step, and yes, they work quite well. offshore racing boats, and even some performance fishing and cruising boats, use anywhere from 1 to 4 steps in their design. they allow a much faster ride with less hp. but they also handle much differently, and there have been plenty of people that have rolled their boats while turning, because of the steps.<br /><br />sounds like scott is the man to ask speed questions. would be interested in his opinions/thoughts on the sanding of a hull vs. waxing, and it's application.

 

[walleyehed]

Re: Need For Speed

(I had sanded a hull I had and only gained 1.5 mph by gps over the waxed hull. Been there - done that!)<br />

Hmmmm.....That's a 4-5% gain! quite substantial, all things considered.

 

[phatmanmike]

Re: Need For Speed

sell it and get an outboard

 

[Gorilla978]

Re: Need For Speed

I think the reason a dimpled hull will allow for a higher top speed is the same reason a dimpled golf ball travels farther/faster than a smooth one. The air/water molecules stick to the smooth surface while the dimpled surface breaks up the air/water flow allowing for easier travel through the medium.<br /><br />/Rant off <br /><br />-Mike

 

[scott begovich]

Re: Need For Speed

NO WAX<br />We run a scuffed hull with very sharp chines.<br />It has made a difference of about 1-2mph.<br />Not a big deal unless you are running wide open for 50 miles, in our case it could be the difference between winning and losing.<br />The problem with steps and sanding are high speed turns. The boat tends to slide and if your not careful you will hook and roll