Plastic Discs to fill Pintail Fin Holes?

[jimboe]

I have a Dragorossi Pintail and want to make a couple blank discs to fill the fin-mounting holes in the hull to reduce drag. DR rep Tony Zanetti said he did not know of any pre-made blank discs available and said he once made some out of plexiglass. I bought a 3/8" thick piece of polycarbonate, but without a mill and lathe, it would be a big job to hack and sand the discs to a good fit in the hull.

I think it would be much easier to get a 2-part polyurethane casting resin such as TAP Quik Cast, or Por-A-Kast, and pour it directly into the disc holes in the hull (so I don't have to make a separate mold). I don't think the resin would adhere to the HDTP hull, especially if treated with a release agent (silicone spray?). I would put long screws in the hull inserts so the resin doesn't get into the insert threads. Then I could unscrew them when the resin cured, remove the discs, counter-sink and re-install them with panhead screws, and sand lightly for a clean hull surface.

My main concern is that the heat from the catalyzing resin doesn't harm the hull. The peak exothermic temperature for the TAP Quik Cast is 170'F which I would think would be well tolerated by the hull plastic, especially if I cooled the inside of the hull while the resin was curing.

Does anyone have any wisdom or suggestions to share on this project?

Thanks,
Jim

[design71]

I did this with a polyester resin, the heat had zero effect, and it will not stick to the plastic. I did not put screws in the taps thinking the resin would stick in there and keep the discs from falling out. One upper Green one and one had fallen out. A little gentle pressure with a screw driver popped out the other. If you out a little wax on your boat and the screws you should not have a problem. If you want it to be perfectly flush with the bottom of the boat you will have to do one at a time and lean the boat slightly. The surface tension of the resin is such that you will have to sand it down as well.

[DanH]

Why? Is the drag really that significant? I can't say I've ever noticed it...

Why not just use the fin disc's with the fins taken off them?

[jimboe]

Thanks for the replies, guys.

You raise a good point, Dan - is it worth the trouble? I'm pretty conditioned to make things work smoothly. I patch the holes in the bottoms of my skis and I think it's a carry-over to want to patch them in my boat. The Pintail has a reputation as a screamer on green waves so I'm kind of surprised DR doesn't make blank discs for those of us who are a little obsessive-compulsive about having a smooth hull, or at least make it clear in their literature that having holes in the bottom of the boat doesn't create a noticeable amount of drag.

I'll see how much the DR fin kit is. I suspect it costs more than the $30 for the polyurethane resin, which is a lot of money to fill a couple shallow holes. Hopefully, I'll get distracted by another project and leave the holes alone.

Jim

[DanH]

I've paddled the Squashtail & Pintail a lot without fins and I have to say, I haven't noticed any drag... I think you'd probably generate more drag with a trailing PFD strap or a cag sleeve trailing in the water.