Replacing Through Hulls

[delmarrey]

Originally Posted by captain58sailin

One of the places you need to inspect very closely is where the mushroom meets the threaded shaft of the casting, I have found them to have small cracks after being on the vessel for a long period of time.

Which brings up how tight the thruhull should be screwed in.
IMO it only needs to be tight enough to squeeze out the excess sealant then stop. It's not supposed to hold anything in place except itself, and create a water tight seal.

It should also be pre assembled w/o sealant to make sure the threads have been cut off at the right length. A quick procedure would be to screw in the thruhull piece and what ever excess amount is sticking out, that's what needs to be cut off. This all after the seacock has been mounted and sealed on the inside.

[patr1707]

Since we are on the subject...

The sea cocks on my boat are frozen, I was wondering if you know what type they are (see picture) and the best way to free them up and service them? Any advice would be great. Thanks! Pat

[Sailorman375]

Yours ar Sparton Marine. See Mainsails site for renewal instructions. You basically disassemble and regrind the plug to the body, grease and reinstall.

[Rhapsody-NS27]

Originally Posted by patr1707

Since we are on the subject...

The sea cocks on my boat are frozen, I was wondering if you know what type they are (see picture) and the best way to free them up and service them? Any advice would be great. Thanks! Pat

Servicing Tapered Cone Seacocks Photo Gallery by Compass Marine at pbase.com

[Cheechako]

Those are tapered cone seacocks. Loosen the nut(s), protect the threaded end of the shaft and tap (large hammer) toward the handle. They should break free. I've never re-ground any that I've done; I simply clean them up and do a last pass with WD40 and 400 grit wet paper to brighten them up. Lanolin works great on them, they will likely never seize up again, however, I see you are in northern waters and lanolin will make them turn slow and with some effort in cold water. They wont stick but willl be a little hard to turn quickly. If you dont like this, then I would use grease.

[iLog Sailing]

To add some other insight, if you have never done this before it's worth having the local boat builder working in the yard provide one man of skilled labour and your husband work with them for the day. There is numerous technique which turn an average job into a good one and first time around the block its nice to have a expert hand, small tips like applying a rasp file to the underside of the skin fitting to help sikaflex adhere are the kid of tips the experts bring.
Ahead of the scheduled haul,out you need to have purchased all required hardware, skin fittings, valves and hose nipples, hose claps etc, you will find a variety of sizes around the boat so take a rule and measure the existing diameter as best you can.

I would allow one day out of the water on your own to remove old hoses and remove old skin fittings, this is often done by grinding the face off skin fittings as they are to far gone to unscrew so be prepared with grinder and rubber mallet.

As a rule of thumb, replacing the entire skin fitting every 10 years is worth doing, that should include all components, hose clamps and I usually replace hoses where practical as often they are much older, prone to perishing and lack flexibility so it's nice to clean house and the hose and clamps are a small cost to do the job well. In the case of the head area, the hoses should be the sanitary type and these should be refreshed every 4-5 years to avoid the inherent small from marine bacteria build up. Good luck.

[Cheechako]

and dont forget to buy a thru-hull wrench! they are cheap...

[Cptn Happy]

Ditto on Mainsail's instructions. I followed them carefully when replacing my old-style Groco seacocks w/new Groco tru-hulls and seacocks. I am very happy w/the results and plesantly surprised at how easy it was. Couple of observations: If you are going to diy you will be wise to get a "step wrench", pictured in post #22 from Jamestown or Hamilton Marine; the original seacocks were bolted thru the hull; the new seacocks had a different, triangle shaped pattern. I talked to the tech at Groco and he said in normal service not necessary to thru bolt. I ended up using lag bolts long enough to penetrate the epoxy coated plywood backing plate and approx 1/2 of the hull (I've got a thick hull). Both pieces were snugged down togeather and bedded in 5200. They ain't going nowhere!