How smooth should the bottom be?

[msc1212]

I'm applying Interlux 2000e to my hull after spending the past few weekends stripping my E35 to the gelcoat. What kills me about this product is that I spent weeks stripping, sanding and fairing my hull to a beautiful smooth finish and then the 2000e goes on with an orange peel texture that everyone says is normal for the product whether you roll it or spray it. I'm rolling. The debate then becomes, do you sand the hull after applying 7 coats to return the hull to a smooth finish or do you leave the orange peel. At the marina today there was a healthy debate about which is faster-smooth or peel. One engineer pointed out that smooth is old school thinking- a shark doesn't have smooth skin and goes very fast- the air bubbles created by its motion through water acts like ball bearings. Last summer we saw the application of this idea in the swim suits worn by olympic swimmers. No one had a response to this except for disbelief because of years of accepting the conventional wisdom that you want the hull smooth. I'm turning to all of you- smooth or orange peel? Which would make the boat faster? Thanks very much for any input. Cheers

Michael Cullen
Impromptu

E35mk11 1970

 

[Emerald]

The ball bearing theory of turbulence is not new, and I knew a fellow who raced small boats (laser type things) swearing by a "rough" bottom instead of a glass smooth one. Also, on the gearhead side of my life I immediately think of the folks at Metric Mechanic who specialize in BMW engines. They have a nice write-up on this, and I think the aerodynamics of porting a head flow (ugh) over to the hydro side of our boats. Here's a link to a write up about this:

http://www.metricmechanic.com/catalog/surface-turbulance.php

So, for no other reason than it's a ton of time, and I think there's wiggle room here on theory, I'd leave it with orange peal. Besides, that was the justification I went with last spring as I had the same experience with the 2000E on Emerald.

 

[rwthomas1]

I think honestly, if there was any difference at all between smooth or "rough", in any boat other than full-blown race boats it won't be measurable. Do whats easiest. RT

 

[SASSY]

Smooth Bottom

Rolling and tipping will make a diiference in eliminating orange peel. After you apply the paint to a section with a roller take a light haired brush and drag it length wize across the treated surface, this will rermove air bubles in the paint and also stop runs. Some recomend rubbing the last two coats down with newspaper after it begins to get tacky. I'm not sure if the newspaper works but some people swear by it. Good luck.