Replacing original 47 yr old thru hulls

[pcmm]

Originally Posted by Sirzones

I’m using bronze thru hulls with brass ball valves
I’ll post a picture off my old thruhull

Why brass valves? that's just a bad idea!

[rwidman]

Originally Posted by Sirzones

I’m using bronze thru hulls with brass ball valves
I’ll post a picture off my old thruhull

Brass is a very poor choice because it will deteriorate in salt water.

You should be using bronze ball vales, but only if you cannot fit proper bronze seacocks.

[Sirzones]

Bronze ball valves are not available at any marine store in my area, I’ve asked all the major marine stores and have not found one knowledgeable person that even knows the difference between bronze and brass 🤬
The new plastic style valves are not available in eastern Canada

[C420sailor]

Order them online. Do what you must to get bronze instead of brass. Groco makes them.

No kidding, brass is unacceptable. It will blow your mind to see how easily (and rapidly) brass will crumble after the zinc is lost—and it won’t be evident until it fails.

[PerfectPirate]

In Canada, Western Marine in British Columbia, along with their Ontario subsidiary Transat Marine, acts as a distributor for Forespar products, which include Marelon valves. My local chandlery sources from them. Binnacle.com is a Canadian east-coast on-line retailer selling Marelon valves and Groco products. Of course, Defender.com in the states is the ultimate last resort for finding anything. You can call Groco directly and get solid technical support from them. I have done so.

That said, encourage your local chandlery to contact some of these suppliers and develop a source for the product. We need to keep our local chandleries alive and healthy, or we will all be screwed when the time comes for maintenance products and support. Just try getting bottom paint or solvents shipped to your home by FedEx. Plus, they too are a part of our boating community! They deserve our loyalty and support, even if it does cost a couple of extra bucks above online prices. The payback is in their long-term support of local boaters.

[pcmm]

Originally Posted by Sirzones

Bronze ball valves are not available at any marine store in my area, I’ve asked all the major marine stores and have not found one knowledgeable person that even knows the difference between bronze and brass 🤬
The new plastic style valves are not available in eastern Canada

Just order bronze seacocks from The binnacle.

[Sirzones]

I’ve decided to return all the brass ball valves and order bronze to match my thruhulls

[wingssail]

Originally Posted by PerfectPirate

The substance sealing your old thru-hulls is grey butyl, usually sold in the form of a tape. It is the same substance which seals the multiple layers of the hull-deck joint in all C&C's (also Hinterhoellers (Niagaras & Nonsuches) and Ontario yachts) and, as all owners of those boats can attest, it remains flexible and oozy indefinitely. This is what makes it a superior sealant, as it easily accommodates flexing and movement, and will literally reseal itself if movement should momentarily break the existing seal.


After 37 years of mounting and sealing thru-hulls and deck hardware, I have learned this: anything which I seal with butyl tape stays sealed and never leaks, any other kind of sealant (except possible 5200) will eventually dry out, or yield to UV, or have its seal broken by movement. At this point in my sailing career I bed everything with butyl tape, including the new thru-hulls which I am installing to my classic plastic baby. As a bonus, when you remove a piece of hardware which has been sealed with butyl, you can usually clean it up by simply "rolling off" the old sealant with your fingers. Since it likes to stick to itself, you can clean off threads by using a lump of old sealant to "stick and pick" the remainder out of threads, etc.

I learned the hard way that butyl tape will melt and ooze in extreme climate heat. I bought a couple of rolls at a swap meet and used some in two places on my boat: an acrylic plastic skylight over the salon table and on a footrest/batten on the aft deck, both also held in place with screws or bolts.

Within a few days in the Mexican heat the butyl ran like pine pitch and dripped into my cabin. It might be OK in an underwater application but I won't any longer use it as bedding for any deck fittings.

[alaskanviking]

Brass will get eaten away pretty quick. i order my bronze usually, if you at any time have to go to a local chandlery or west marine your paying double. even at the chandlery you will find brass and red brass fittings with the thru hulls and fittings. i found only Groco makes bronze short nipples, you will have to replace red brass at some point, its not worth installing on your boat with raw water. some locations you can only find dezincification- resistant brass, sometimes its labeled as "DZR". the alloy is still brass similar to red brass but it doesn't have as much zink to get pulled out. again a some point you will have to replace them. you can order real bronze fittings to ensure you get bronze. frustrating in the least. another problem is different bronze alloys can interact, it is probably minor but i ended up staying with the same manufacturer for all my bronze to ensure its the same alloy.

i highly recommend following the info from https://marinehowto.com/replacing-th...-and-seacocks/

i did it three ways,
1) glassed the backing plates into place and then drilled the big holes, works when your drilling the flange bolts all the way through the hull.
2) drilled the hole and installed the studs then glassing that into place and drilling the big hole.

i found there are alignment issues with both 1 & 2 that can make it difficult to get everything aligned and in place to initially start the thread. that means it requires you to have a second person to help align things. there were a few scary moments here that worked on a test fit, where i had a helper, but didnt work later after i had everything caulked. its maddening frustrating and was one of the few points in my life i was close to full out tears. everything did work in the end, but i don't fully recommend these.

3) manufactured the backing plate with the big hole and installed studs. drilled hole from outside. coat the thru hull with mold release and then a few passes of Teflon tape down its length. so the epoxy wouldn't stick. put the thru hull in the hole, i wedged a spare boat tripod stand against the thru hull to keep it in place. make up your thickened epoxy, i used silica and 1/2" fiberglass strands to make a thick epoxy kitty hair consistency. butter up the back of the plate and install it over the thru hull. use a thru hull nut to tighten the plate until the face of the nut was flush against the backing plate and therefore square. I attempted to just use the thru hull and not the nut on the last two but i found its close but still slightly misaligned one i managed to get myself the other had to have a helper to assist. make a good epoxy filet all the way around the plate. the plate will never come off the boat, or get soaked with water! the epoxy WILL squeeze along the threads of the thru hull and make STRONG epoxy threads. you have to resist beating the thru hull out and unthread the thru hull from the outside, you may have to use a little heat from the heat gun. you have to run the hole saw back through to correct any minor misalignments and remove the threads. when installing re-read the seacock directions on sealant. you put sealant on the mushroom, base threads of the thru hull and the flange of the seacock/tri-flange adapter. if you don't there is space for a weep of water to get out from under the flange, which is upsetting and expensive to redo. its more of a pain to clean but now i am a strong advocate of lots of sealant and lots of cleanup afterwards for thru-hull install. Also verify and re-verify that you have your seacock handles in the correct location so you don't have to do an insane amount of cleanup and redo the next day. it took a few days to fully cure (temps 50's-60's). nobody makes these and its time consuming but these backing plates are well worth it.

to make these last set of backing plates i had to borrow a drill press to ensure the holes were straight. ran it at slow metal speeds. heavy clamping is a necessity if you wish to live through the experience. we used water in a spray bottle to lube and cool the hole saw and bits. the back side i used a forsner bit to make a cup just slightly deeper and bigger than the bolt head. then i ran through a 5/16" tap with my hand drill. this wasn't the best as a few taps got slightly kitty wonkus and had to have the bolts bent slightly to align with the flange for install. not many drill presses can do a power tapp hole like that, and these came out very close especially as we learned to do it better through the process. i cleaned everything with acetone and sanded the bolt head slightly to scuff it up, before installing them in the plate. its a bit shocking how strong G-10 is in this regard as we torqued the bolt tight. later we did this to a scrap and put all out force on it but still couldn't get it to strip out. this keeps the bolt tight in the threads so there was no epoxy leakage. we then filled the cups and encapsulated the bolt heads with thickened epoxy, sanding it smooth after it cured and scuffing up the back of the plate ready to be installed. test fit several times. if you have to bend a bolt then you put the plate into the vice and put two nuts on the end of the bolt. tap it with a hammer to correct alignment.

marine how-to suggests you use 3/4" G-10 plate for the backing plates, however on my smaller ones i found 5/8" was acceptable. the thick stuff isn't cheap. i found some 1" plate sections at the plastics shop in San Diego that i picked up cheap so some of mine are made with that. there should be a plastics place by you and its worth the time to rummage through their scraps if they use G-10.

i paid extra for the big heavy duty Groco "BV" rebuildable seacocks. there is a cheaper non rebuildable version "FBV" that is similar to what's available by the other brands. the BV seacocks are good for the smaller sizes but they get prohibitive if you have to go over 1.5". i think the better bet it the flanged adapters with a ball valve, as its as strong/stronger than the FBV, but still gives you the ability to replace/rebuild while the boat is in the water like the BV. this flanged adapter setup is much cheaper than the BV seacocks and the same or slightly cheaper than the FBV.

[alaskanviking]

don't use butyl below the waterline, use Sikaflex or 3m 4200. 4200 turned yellow on some of my fittings above the waterline so i use Sikaflex mostly now. i love butyl though to seal up fittings on deck.

regardless order your sealant, unless your lucky and found a place with normal prices locally. there is a burlap place in Norfolk that has fiberglass supplies and sealants for a similar price as online.

when I miscalculated the amount to re-install my rub rails, i ran out and got stuck. Either wait 3 days for an order to get in at $12 a tube OR pay $35 each tube at west marine! i seen similar at a local chandlery also, so you have to shop around.

[jay2rocket]

I am following this technique for my Ericson 25

TritonBoatWork: Thru-hull Flange Plate and Marelon Flanged Valve Installation.

is 'doubly safe'

[Wireless1]

I don't think your thru-hulls with the 90 deg. L before the ball valves are an approved method. I had a similar situation where there was not enough vertical space so I found the shorter FBV valve (plus backing plate) with the 90 deg fitting after it to be a good solution.

[Sirzones]

Finally found correct valves at the Binnicle in Halifax, NS

[Sirzones]

Just wondering if G10 backing plates are not readily available, can I make them from marine plywood coated in epoxy and then glass onto inside of the hull?

[Celestialsailor]

Originally Posted by Sirzones

Just wondering if G10 backing plates are not readily available, can I make them from marine plywood coated in epoxy and then glass onto inside of the hull?

That's what I do. Cutting G-10 on my Grob band saw ruins very expensive blades. When you hole saw through the the backing plate be sure to slightly over size it coat it with a few coats of epoxy or even a layer of cloth with epoxy. It helps to seal it from water.