engine thru hull seacocks

Why do you feel the need to change them? If they open and close (not frozen) and don't show any real signs of corrossion then I wouldn't see a need to change them. If I had to guess they're probably 2.5" but do not quote me on that. You should be able to measure the thread size on them......or guess by looking at the size of the fittings attached to the seacock.....

Hi,

I replaced mine about 8 yrs ago with full flow ball valves.
Mine were operational but in a location that was hard to reach especially if it were urgent.

I bonded the valve body into the bonding system as the original was.

I have an '80 - 46 and the seacocks were located aft of the shaft log and on the outboard side.

I did it with a helper and it is not a bad job.

I replaced the wood backing board with treated lumber while I had it apart and used 5200 for bedding.


Never had a problem. They need to be full flow valves if you choose ball valves.

The hardest part foe me was getting the short piece of 2.5 inch hose from the valve to the oil cooler. That took help and a small porta power.

Good Luck

I am replacing almost all thruhulls and seacocks on my '75 Post Project boat (see separate thread). The head valves were stuck, the generator gate valve handle was rusted off and stuck, and the engine intake gate valves were functioning but iffy. I figure why take chances when it comes to holes in the bottom of the boat.

I removed them by cutting the mushroom head on the bottom of hull with a 4 1/2" grinder and poking the thruhull with seacocks still attached that I otherwise couldnt loosen up into the hull.

I plan to use 1/2" fiberglass panels purchased from McMaster Carr as backing instead of wood backing as is on there now. 5200 was my plan as well.

One thing I have yet to decide is going with flange seacocks that have matching NPS threads to connect to the NPS threads of the thruhull vs. simpler and cheaper NPT/NPT seacocks. Everything you read says the former is much safer. But others say it is not a big deal. And my other boat, a much better than average quality sailboat, has the unflanged versions on all thruhulls and after 20+ years has proven not to be a problem.

i added some internal sea strainers for the mains.
After finding a mussel farm in my gear coolers.

My Post only came with the external wedge type sea strainers.

Now it has both.

I am ready to replace a few through hulls which are through bolted to the outside of the hull. That should be fun.....

here is a pic of the sea strainers i put in the late 80's 46 Post.

they are mounted on a fabricated bracket on the stringer inboard of the engines near the battery box.

The strainers are 3inch Groco stainless steel.

I can flush/winterize the engine by shutting the valve and screwing a standard PVC pipe into the clean out.

see pic

Looks good. I am adding internal strainers as well and have eliminated the outside wedges. I too have to deal with old bolts and relate holes in the process.

Your seacock in that shot - is it a NPS/NPT flange or just a straight NPT/NPT without flange? If the latter, is it mounted real close or even flush to the collar nut of the thru-hull?

Thanks

it is the flange type, you cant really see it in the pic.

sorry for the pic quality

I'm not sure why you would eliminate the wedges for a flanged thru-hull. The flanges serve two purposes, direct the water flow while underway and provide a rough screen to keep stuff from being sucked in. This is not so critical for ancillary devices like head intakes but for mains,gennies and a/c you want all the flow you can get.

I agree and it's always easier to replace with what you already have

Thanks RT46 - looks like a good setup.

Thanks to others for good advice on wedges - not a problem on my sailboat! But I now understand the benefits for the Post.