thru-hulls

[piers]

Is it oK. to use 3M 4200 fast cure as a bedding compound on thru- hulls that are below the water line?I like it because you can disassemble at a later date but I wanted to make sure it was strong enough for sealing below the water line in the marine enviroment.<br /><br /> Thanks in advance<br /><br /> PT

 

[snapperbait]

Re: thru-hulls

Yep..<br />

 

[jimmythekid]

Re: thru-hulls

after cutting the hole, would be a good idea to seal the freshly cut hole with the resin of your choice before installing the fitting that way if any water does leak in it will only goto the bilge instead of into the hull.

 

[ThomWV]

Re: thru-hulls

If you mean a thru-hull transducer, sure, you can use just about anything to tell the truth. What you're really doing is creating a gasket, not actually glueing anything together. That's why the trick to really getting a good seal is to do this. Clean around the hole, inside and out, and the thickness of the hole's sides too of course. Wipe it with a rag with acetone at the last moment. Don't use sealer on the inside, just the outside and hold the fitting on the outside while someone else, on the inside, runs down the holding nut as tight as they can get it by hand, but no wrench. They should be able to get it tight enough that you see a bead of sealer squeeze out all around the fitting. Let it stand and set. Come back the next day with a set of channel locks and tighten up the nut. What you will have done is create a seal and gasket the first day and pulled tight into it the second. It won't leak a drop.<br /><br />Thom

 

[piers]

Re: thru-hulls

Thank you all for the quick reply's.Thom when you say do not put sealer on the inside do you mean on the flange of the lock nut that you tighten down on the inside of the hull? Also is it necessary to put any sealer on the threads of the thru-hull?My day time temps here have been hovering around + 6-7 C. The 4200 says to have a min. of + 4 c.To get a good seal should I try to heat the whole area up a little warmer?<br /><br /> Thanks <br /> PT

 

[ThomWV]

Re: thru-hulls

No, there is no real reason to put sealer on the threads and I try to avoid getting even a little on the threads because it can make getting the nut off so hard later. However a little bit behind the flange nut, on the flat of the nut that contacts the inside of the hull I don't think is such a bad thing but I don't try to do that purposfully. I guess my point is that you really don't have to use a whole lot of this stuff and it doesn't have to be everywhere. When you have to remove a few old ones that have been put in with 5200 you come to appreciate the guys who did a neat, but sparing, job with the stuff.<br /><br />I think we all understand and have been caught up in the notion that if some is good then more is better, however in this case some is real good and more is just one hell of a mess.<br /><br />Thom

 

[piers]

Re: thru-hulls

Thanks Thom,<br /><br /> That sounds good.I have two thru-hulls to replace that are below the waterline and I know this stuff can get pretty messy.I will post the results, I should be able to get to them by this weekend.<br /><br /> PT

 

[TwoBallScrewBall]

Re: thru-hulls

Only thing is.. If the hull is wood or wood cored, seal both sides of the fitting. You don't want water that may splash somehow on top (in bilge, etc) to get into the wood. If it's fiberglass no need to seal the top side.

 

[piers]

Re: thru-hulls

It is infact in a transom which from the inside is first gelcoat,1 1/4 in. of wood then 1 1/4 in. of fiberglass.I have resined the inside of the hole now it is time to put on the thru-hull.I think it can not hurt to run a bead of th 4200 on the flange of the lock nut just incase. The thru-hulls are both located in the bige area.Thanks for all of your suggestions.<br /><br /> PT

 

[cc lancer]

Re: thru-hulls

Another thing to consider is using brass thru-hulls rather than the cheap ones. There has been boats that sank because of cheap thru-hulls cracking.

 

[18rabbit]

Re: thru-hulls

There are two kinds of thru hulls; inexpensive plastic/nylon for use above the waterline (sink drains, gray water pump out, etc), and brass, bronze, or ss for use below the waterline (engine cooling, head flushing/pump out, live wells). Of course, the metal thru hulls can be used above the waterline, but never the plastic ones below the waterline…see CC Lancer’s comment above. If you use the plastic kind (above the waterline only!) you should paint it to protect it from uv. I don’t like the plastic ones and prefer to use metal all around; ss above the waterline and bronze below.<br /><br />When using metal thru hulls below the waterline you need to be ever mindful of dissimilar metals and galvanic corrosion. The only thing that ever connects to a below-the-water-line thru hull inside the boat is a ball valve. Never connect plumbing or hose directly to a thru hull. All ball valves must be immediately accessible. Since bronze ball valves are commonly available, I use bronze thru hulls and avoid the whole issue with different metals. Also, all of my thru hulls have a nifty green AWG 10 wire connecting them to the boat’s bonding system.<br /><br />The ball valves need exercise and should be opened and closed several times a year so they don’t get stuck in either orientation. Every couple years they need to be removed and inspected/rebuilt to replace the seal inside. So applying some non-conductive lubricant to the threads of the thru hull before fixing the ball valve to it is a good idea.

 

[piers]

Re: thru-hulls

All great comments.What do think about attaching the bronze ball valve that seems to have female tapered threads on to the bronze thru-hull that has male straight threads.I have also considered using the marelon ball valves.They have a straight female threads and apparently (according to the forespar websight) can be used quite safely with bronze thru-hulls.I had read that useing taper to straight will not be a strong enough connection and could be prone to leaks.<br /><br /> PT

 

[18rabbit]

Re: thru-hulls

Some of that marelon stuff costs more than its bronze counterparts. If the ball valve is located somewhere such that there is no chance of anything ever smacking it you should be ok. I have no experience with the marelon ball valves (only vented loops). Don’t know anything about maintaining those valves. I can’t answer your question about tapered vs. straight threads...never seen tapered threads on a ball valve. Hopefully someone else with more experience in that area will weigh in.<br /><br />It is recommended that you always have a wooden bung plug near every thru hull that can be used in an emergency. If you go with the marelon, definitely have an appropriately sized bung plug that can be pounded in if needed. If you don’t have immediate access to the ball valve or not enough space to pound a bung plug, I’d be inclined to go with a bronze valve. Bronze ball valves are common and not that expensive.

 

[piers]

Re: thru-hulls

Thanks for all the input.Thru-hulls are something you sure want to have done right.I have now finished installing a 2 bronze below waterline thru-hulls.One for an aerator head and another for a raw water washdown.I also replaced an above waterline thru-hull for a sink drain with a marelon product.All went well but I guess the true test will be when I float the boat this spring.<br /><br /> PT

 

[cc lancer]

Re: thru-hulls

Also, all of my thru hulls have a nifty green AWG 10 wire connecting them to the boat’s grounding system.<br /><br />18Rabbit: <br />What a great comment, I had never though about using the brass through hull for a ground.

 

[snapperbait]

Re: thru-hulls

What Rabbit should have said is, <br />

Also, all of my thru hulls have a nifty green AWG 10 wire connecting them to the boat’s Bonding system.

Don't want to be grounding electical items directly to a thru hull or other underwater part..

 

[cc lancer]

Re: thru-hulls

What about the out drive?

 

[18rabbit]

Re: thru-hulls

Thanks, Snapper. Yeah, the whole bonding/strapping/grounding thing is not without a boatload of controversy. I probably shouldn’t even have brought it up ... but hey! the crimping vs. soldering thread is slowing down.

 

[snapperbait]

Re: thru-hulls

LMAO...