Lapcat in Progress

[Gaztech]

Lapacat was sanded and primed this weekend.... How should the bottom be finished to be made race ready ?? Lightly sanded, Finished sanded and waxed, or what.... Thanx Gaz B)

 

[Foolwitools]

Hi Gaz,

You'll get a few different answers about bottom finish prep.........the full size unlimited guys use a graphite impregnated coating. I know cleaning and waxing my 14' runabout below the waterline was a big improvement. some outrigger guys say 400 or 600 grit wet sanding............

try to keep the lower most edges of the sponsons sharp. don't smooth or round them when you sand. the transom bottom edge should be square and sharp also.

Good Luck,

Bob the fool :blink:

 

[Gaztech]

Thanx for the reply... Any more suggestions from the TOP GUNS.... GAz

 

[Gaztech]

Thanx for the reply... Any more suggestions from the TOP GUNS.... GAz

:unsure: 2,600 Members and is this the way to go ???? Thanx Gaz

 

[Jack Garcia]

Hi Gaz,

You'll get a few different answers about bottom finish prep.........the full size unlimited guys use a graphite impregnated coating. I know cleaning and waxing my 14' runabout below the waterline was a big improvement. some outrigger guys say 400 or 600 grit wet sanding............

try to keep the lower most edges of the sponsons sharp. don't smooth or round them when you sand. the transom bottom edge should be square and sharp also.

Good Luck,

Bob the fool :blink:

If you want the most from your tunnelhull and are willing to take the time to do it, there are some easy tricks you can do to enhance its performance. Note: This next part of preparing your boat should be done before you have applied any paint. It involves "tuning" the sponsons. To tune the sponsons, here are the tools you'll need. A straight edge such as the steel ruler on a carpenters square, some 120 or 180 grit sandpaper, and some 320 and 400 grit wet or dry as well. Make yourself a sanding block of 1" thick pine that's 10" or 12" long by 3" wide. Using contact cement, glue a strip of the 180 or 120 grit sandpaper to the sanding block. Don't just wrap the sandpaper around the block it won't be flat enough. You will also need a small, sharp, fine tooth flat or half round file.

Your engine is the most important part of your boat. It transfers the horsepower to the prop that pushes the boat forward. How fast depends on how much horsepower the engine is generating and how well you have set up the boat. One part of setting up is to

make certain that the hull bottom is correct. Are the riding surfaces flat and true? Are the edges sharp? Are the sponsons true and equally flat?

These irregularities occur mostly on fiberglass hulls. Polyester in particular. (Fiberglass Resin). Epoxy resin hulls are not as susceptible as polyester, but its good practice to check the bottoms on all boats, even wood and new boats. This is part of fine

tuning that allows you to get the most out of your boat hull. It's important that sponsons on tunnels are equal horizontally. To check, place the hull, sponsons down, on a perfectly flat board. (It's important that the board is PERFECTLY FLAT, or else you

will get a wrong reading.) Position the hull so that you can see any light that may show through, indicating that the sponsons are not equal. These must be made equal to start with. Using the sanding block, sand equally on both sponsons one at a time, concentrating on the lowest part until you are satisfied that they are both flat with no light showing through. Next thing to check for, is an irregularity on the riding surfaces. It may be a bow (Rocker), or a dish, (Hook). Place the straight edge longways on the sponsons, and slide it from side to side. As before, position the hull so that you can see light that may show through between the straight edge and the sponson. Hooks will appear mostly near the transom. Don't try to remove a hook until you have first sanded the rest of the bottom flat. If there is still any indication of a hook, roughen the area by sanding, and fill it in with putty made of epoxy and micro balloons. Re-sand when the putty has hardened, making certain that this area is equally as flat as

the rest of the bottom. Another area that needs attention are the edges, such as the back bottom edges, steps, and inside sponson edges. These should be sharpened. The reason for making edges sharp, is that water tends to cling to rounded surfaces, causing

friction. By sharpening, you are allowing the water to break away cleaning, thus adding to your boats speed and maneuverability. Use the file to very carefully sharpen all of the steps.

After you have straightened, flat sanded, and sharpened, you are ready to do the finish sanding. Use the 300 grit wet or dry sandpaper to smooth the rough areas. (Use the sandpaper wet). Now do your finish sanding with wet 400 grit. I may go overboard, but I follow the 400 grit with 800, until I get a glaze.

Good luck Gaz.

 

[Gaztech]

Jack

Thanx for the tips on the setup. We will lay it up and take a look. Gaz

 

[Jack Garcia]

Jack

Thanx for the tips on the setup. We will lay it up and take a look. Gaz

You're very welcome sir.