A petty little thruhull dilemma

Figment · Post by **Figment** » Sun Oct 30, 2005 7:41 pm

A PO had outfitted the boat with a speed/depth instrument which was dead by the time it got to me. The speed impellor's thruhull is in the bilge, roughly midway down the portside.

I've left it in place so far. I apply a bead of polysulfide to the inner rim of the cap and screw it down tight prior to launch, and it never leaks a drop.
I use it as one might use a garboard drain, I guess. I leave it uncapped in the winter (handy to prevent excess rain/meltwater buildup), and it makes draining the fuel system at the end of the year a snap.

I no longer need the bilgewater relief, and the whole fuel draining thing seems like a petty reason to have an otherwise useless hole below the waterline. I'm considering removing the thruhull and glassing it over.
Or possibly removing the thruhull and installing a TRUE garboard drain fitting.

What would you do?

bcooke · Post by **bcooke** » Sun Oct 30, 2005 8:08 pm

Is the hole in an ideal location for a drain? If not I would fill in the hole and place the drain in the best possible location. Filling holes in the hull is just too easy to compromise the drain location.

-Britton

Post by **Tim** » Mon Oct 31, 2005 6:52 am

Ditto.

hawkeye · Post by **hawkeye** » Fri Nov 04, 2005 4:17 pm

I have the same problem with the same transducer. If I pull the transducer I have to patch the hole with polyester not epoxy...right? That's the biggest reason I haven't pulled the thing out, I just don't want to mess with polyester resin. I mean...it just leaks a little...what's the big deal about a leak anyway...what's a bilge pump for? hehehe

Post by **Tim** » Fri Nov 04, 2005 4:28 pm

hawkeye wrote:If I pull the transducer I have to patch the hole with polyester not epoxy...right?

No. Use epoxy for all repair work. It's the right choice.

Polyester is OK for building new boats, but that's the extent of it. Perhaps you've heard some talk elsewhere of keeping your repairs "homogeneous" with the original construction by using polyester resin...total blather. This is just what the cheapos say to help justify their refusal to pay for the more expensive epoxy resin.

Not that I have an opinion or anything...hehe

Figment · Post by **Figment** » Fri Nov 04, 2005 6:46 pm

A magazine (I can never keep track of which one) recently ran a half-assed how-to article on glassing over abandoned thru-hull penetrations. The professional they brought in advocated the use of vinylester resin over polyester or epoxy.

His reasoning was interesting though. Vinylester cures more rapidly than epoxy, which allows the inner layer(s) to cure completely, be sanded, and the outer layers to cure and be sanded and painted all in one day.

I can see how that might be advantageous to the journeyman boat repair guy, but for average joe boatowner I think epoxy is the better choice. The mix ratios are less exacting, and returning to sand things fair another day is not a problem.

I patched this thread's topic thruhull the other day. Fifteen minutes of grinding, ten minutes of cleanup, fifteen minutes of epoxy work (inner and outer layers allowed to cure together) and I was on to the next thing. Probably another fifteen minutes worth of grinding and fairing ahead of me, but that'll all happen as one drop in a much larger bucketload of grinding and fairing.

Post by **Tim** » Fri Nov 04, 2005 7:52 pm

Vinylester resin is a good product, and really should be what boatbuilders use to build new hulls at this point. Of course, it comes down to cost, but vinylester resists some of the hydraulic problems that are an issue with polyesters. The higher end builders are now using either 100% vinylester for the hulls, or at least for the skin layer.

However, vinylester is a type of modified polyester resin, and therefore has much the same qualities as regards secondary bonding--which is, after all, the reason that epoxy is such a better choice for repair work on fiberglass boats.

The ability to cure quickly (as with polyester/vinylester) is admittedly convenient for a contractor, but is only an acceptable choice if the end product is of as high quality. For repair work, where strong secondary bonding is a requirement for quality, I think the contractor's convenience has to come second to providing a quality job. At least that's how I see it.

Oh, and vinylester, while more costly than polyester, is still significantely less expensive than epoxy.

bcooke · Post by **bcooke** » Fri Nov 04, 2005 8:00 pm

A magazine (I can never keep track of which one...)

The most recent Good Old Boat I think. They had the hole filled and bottom painted before lunch.

I remember it because I filled in my holes over several days - a couple of layers at a time (with epoxy :-)

-Britton

hawkeye · Post by **hawkeye** » Mon Nov 07, 2005 12:06 am

Well Tim...now I got a hole in my boat. I think I'm going to need a bigger bilge pump! Seriously, I had to destroy the transducer to get it out, but the weather here in green bay has been cold and rainy so I don't know when I'll get to patchin' er back up. Good thing I just got a Milwaukee heat gun, huh?