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drill a hole in the hull

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hewebb
Admiral

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USA
761 Posts

Initially Posted - 01/27/2012 : 05:58:23

I received a speed meter for Christmas and plan to install it in the next couple of weeks. I have looked at the directions and have to drill a hole in the hull to install the sending unit. That part is not a problem. The instructions do not indicate what to use to seal the sending unit hull opening to insure that it does not leak. What is recommended?

Thanks

1988 WK/SR w/inboard diesel Joe Pool Lake
Hobie 18 Lake Worth

Life is not a dress rehearsal. You will not get another chance.

Edited by - on

DaveR
Master Marine Consultant

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USA
2015 Posts

Response Posted - 01/27/2012 : 06:48:08

With all due respect to the person who bought you the speedometer I'd use a GPS and forget about a hole in my boat.

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redeye
Master Marine Consultant

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3476 Posts

Response Posted - 01/27/2012 : 07:01:40

cell phone...

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Sam001
Vice Commodore

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USA
441 Posts

Response Posted - 01/27/2012 : 07:06:04

and I agree on no hole in the boat :-)

Edited by - on

Stinkpotter
Master Marine Consultant

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Djibouti
9076 Posts

Response Posted - 01/27/2012 : 08:18:00

Yup. Maybe nothing grows in your lake, but if it does, it'll grow on the little paddle wheel, and your speed will read 0. On a lake with no currents, a GPS will give you a more accurate speed plus a lot of other stuff. Mine works in the car (just like a Nuvi) and boat (with full charts). I haven't tried my new iPhone yet...

Edited by - Stinkpotter on 01/27/2012 08:23:04

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 01/27/2012 : 08:22:53

The question wasn't whether he should use the speedo, the question was what sealant should he use for a through-hull fitting. Anybody out there that has put a thru-hull in their boat? What sealant did you use?

Edited by - on

NautiC25
Admiral

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USA
957 Posts

Response Posted - 01/27/2012 : 08:34:47

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by John Russell
 The question wasn't whether he should use the speedo, the question was what sealant should he use for a through-hull fitting. Anybody out there that has put a thru-hull in their boat? What sealant did you use?
<hr height="1" noshade id="quote"></blockquote id="quote">
Yea, let's try to help him out here.

I don't have any experience, but if it were me, I'd go with what Catalina Direct recommends:
This is the high strength stuff, which I'd go with: http://www.catalinadirect.com/index.cfm?fuseaction=product.display&product_ID=990

This is the regular strength: http://www.catalinadirect.com/index.cfm?fuseaction=product.display&product_ID=194

Edited by - NautiC25 on 01/27/2012 08:36:15

Joe Diver
Master Marine Consultant

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USA
1218 Posts

Response Posted - 01/27/2012 : 08:36:34

You have a trailer Howard?

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Stinkpotter
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Djibouti
9076 Posts

Response Posted - 01/27/2012 : 08:37:09

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by John Russell
 The question wasn't whether he should use the speedo...<hr height="1" noshade id="quote"></blockquote id="quote">That's what happens around here--especially in the winter when we're getting feisty.

OK, I didn't do it, but if I did, I'd use Boatlife Life Seal, which is not too adhesive but compatible with plastic (assuming...). I'd tighten the fitting very lightly until the sealer is squeezing out uniformly all around it, let the sealer cure for a few days, and then tighten fully to compress the seal.

That's if I did it... But I wouldn't do it. YMMV.

Edited by - Stinkpotter on 01/27/2012 08:37:46

Ape-X
Admiral

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USA
662 Posts

Response Posted - 01/27/2012 : 09:25:03

Good thread, I may be replacing a faulty unit this year as I now have a chartplotter that this can connect with.

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Stinkpotter
Master Marine Consultant

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Djibouti
9076 Posts

Response Posted - 01/27/2012 : 09:35:14

Ah-HAH. A "faulty unit" in a hole in the boat...

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Ape-X
Admiral

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USA
662 Posts

Response Posted - 01/27/2012 : 09:48:15

well, MAYBE faulty unit, non-compatible with the GPS, and a non-working head unit....btw, how hard is it to close over where the old gages were?

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Joe Diver
Master Marine Consultant

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USA
1218 Posts

Response Posted - 01/27/2012 : 11:13:36

I can't remember if Howard has a trailer or not....but now that the lake is back up (went from 6' low to 1.7' low with this last rain, the one that put all that water in Eddy's boat) Victor should be able to pick you up with his crane over at Harbor One. He charges $250.

Edited by - on

waterbaby
Navigator

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USA
168 Posts

Response Posted - 01/27/2012 : 11:50:54

I have one of those paddles for measuring speed on my boat. It took about a 1.5 months in the Pamlico river before it got weedy and stopped working. It was sweet while it lasted. But I understand now it's a lost cause.

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John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 01/27/2012 : 13:20:45

I have a paddle wheel model as well. I usually launch in April. Around August or so, the speedo gets sluggish. Usually breaks loose after a couple minutes of motoring. When it doesn't, my model is easy to pull out of the thru-hull and switch out with a plug that must've been supplied with the speedo. It was on the boat when I bought it. If you're quick enough with the switch, a small towel laying downhill of the fitting always catches the in-flow of water during the switch. Then you can take your time cleaning the paddlewheel. On a bad day, I think it took 4 maybe 5 minutes of cleaning. Then another 3 second switchout, re-secure the retaining pins and go sailing.

Edited by - John Russell on 01/27/2012 13:22:19

Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 01/27/2012 : 13:50:12

You guys aren't sailing hard enough! Ours works pretty well, keeping pace with the GPS for most of the season, but we hit it with the VC-17 every spring. Its nice to have a backup for when the satellites fall out of teh sky.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 01/27/2012 : 13:59:12

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by John Russell
 The question wasn't whether he should use the speedo...<hr height="1" noshade id="quote"></blockquote id="quote">I'd tighten the fitting very lightly until the sealer is squeezing out uniformly all around it, let the sealer cure for a few days, and then tighten fully to compress the seal.
<hr height="1" noshade id="quote"></blockquote id="quote">

I'm not so sure the tighten twice technique should be used for underwater fittings (Actually, I'm not so sure it should be used anywhere).

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Stinkpotter
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Djibouti
9076 Posts

Response Posted - 01/27/2012 : 15:53:05

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dlucier
 I'm not so sure the tighten twice technique should be used for underwater fittings (Actually, I'm not so sure it should be used anywhere).<hr height="1" noshade id="quote"></blockquote id="quote">The theory I was taught, I think by a rigger, is that if you crank down the fitting when the sealer is fresh and squeeze almost all of it out, the mere process of curing, not to mention stresses later, can cause the seal to be broken. What's your theory, Don?

Edited by - on

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 01/27/2012 : 16:19:47

Don't know what Don's theory is but I was wondering if the second tightening wouldn't break the seal between the fitting and the sealant. I think this would make sense on a stanchion, etc. since they're held in place with through bolts and the stanchion itself wouldn't move during the second tightening. In the case of the thru-hull, the actual fitting moves as it's tightened. At least, that's what it looks like on mine.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 01/27/2012 : 16:44:20

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 What's your theory, Don?<hr height="1" noshade id="quote"></blockquote id="quote">

Well, if tightening a fitting only once will result in squeezing out the sealant, why is it done this way when assembling engines? Also, preventing a fitting from moving will go a long way in lessening the chance that it will loosen over time which may result in a leak. This means the mechanical bond is very important. If you fully tighten a deck fitting, a mechanical bond is made directly between the fitting and the deck. If you allow the sealant to form a gasket of sorts before final tightening, then, however minute, it becomes another element within the mechanical bond that could allow eventual movement of the fitting and if during the second round of tightening, a mounting bolt is inadvertently turned, it could break the seal that had partially set up around the bolt.

Edited by - on

JeanAndre
Navigator

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USA
224 Posts

Response Posted - 01/27/2012 : 16:58:03

Hello all,
The hole in the hull..... I don´t see a problem with the hole in the bottom of the hull provided you plug it with a working or not speedometer.
But to make the hole the way you should that´s the challenge.

Here is a link to a good way to drill holes in a boat:

http://www.boat-project.com/tutorials/drill.htm

Cheers

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 01/27/2012 : 17:41:12

Yup, Life-Caulk and yup, don't drill a hole.

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Stinkpotter
Master Marine Consultant

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Djibouti
9076 Posts

Response Posted - 01/27/2012 : 19:13:09

OJ: I just want to point out that Life Caulk is not considered compatible with plastic, while Life Seal is.

Don: The point about the bolt turning is a good one. In the past, I've suggested holding the bolt head steady while turning the nut inside, to maintain the seal around the bolt. Whether "compressing the gasket" makes a less stable mounting might be dependent on the thickness of the gasket. I tighten until I feel some resistance--probably leaving about a 1/32" gasket that can later compressed to a point where the hardware is virtually tight to the fiberglass. If there's no sealer, it might not seal.

Another variation I've used that might meet your criteria is, after drilling a hole, to cut a beveled "countersink" on the outside using a larger bit. This allows a bead of caulk to form around the bolt, under the fitting, theoretically increasing the contact and pliability of the seal against the bolt. This can be tricky--drill bits in power drill like to grab in fiberglass and go in suddenly. A friend advised putting the drill in reverse for this step--it allows you to cut the countersink gradually. And if someone prefers Don's "tighten once" approach, there will still be a sort of O-ring of sealer around the bolt.

A final opinion: I recommend against straight polyurethane sealers like 3M 5200 for almost everything on a boat except truly permanent joints like hull-keel and hull-deck. It can create havoc when you decide to remove, replace, and/or re-seal a piece of hardware (e.g., Ape-X's above). I have some ugly, first-hand experience with that havoc (gel-coat removal), so I'll stick by that opinion.

Edited by - Stinkpotter on 01/27/2012 19:14:35

Voyager
Master Marine Consultant

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USA
5358 Posts

Response Posted - 01/27/2012 : 20:03:24

I'm not as concerned about the hole in the hull - its basically inert once you get it in place.

The display speedometer is mounted in the cockpit bulkhead, consisting of a 4" hole in a very visible spot. If I had my druthers, I'd druther not have a 4" hole there, so I've kept the non-working speed display in place.

I changed out my old depth meter with a new one. I kept the old display housing, and retro-fitted the new depth guage into the housing. I have no similar strategy for the speedo. I guess I could either leave it alone or gut it. But what would I put inside the little window? I've already got a compass and an inclinometer. I have a hand-held wind guage.

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JimGo
Admiral

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USA
962 Posts

Response Posted - 01/27/2012 : 20:28:12

Bruce,
Make a circular trim piece and put some glass in there, then put a picture up (i.e., make it a picture frame). Or make/have made a wooden plug and have the boat's name laser engraved on the plug. Or use the plug to add a mount for something else (hangers for lines, a cup holder, etc.).

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Stinkpotter
Master Marine Consultant

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Djibouti
9076 Posts

Response Posted - 01/27/2012 : 21:55:42

Bruce--I wondered the same thing six+ years ago (same boat).

I thought about cutting a hole encompassing both instrument holes and putting in a portlight.

Edited by - Stinkpotter on 01/27/2012 21:56:28

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