Rodd,

I replaced all of my seacocks and the backing boards not too long ago.
(Went to Marelon, see plastics article in Blue Water Sailing). None of
the bolts went through the hull. They were all just in the backing
board. As to removing the seacock, I used an angle grinder to grind
off the mushroom head of the of the thru-hulls flush to the exterior of
the boat. With the nuts removed from the bolts, I then just pushed
(large dowel like piece of an old baseball bat, and a hammer) the
thru-hull and valve up into the boat. I made new, thicker pads out of
white oak, sealed with CWF and several coats of epoxy before 5200 glued
them to the hull. I used flush tapered thru hulls instead of mushrooms
for a much fairer hull. No thru-bolts, the thru-hulls hold the
valves. Screws into the oak keep the valve from turning when the levers
are pulled.

Pete

On 3/30/2013 6:47 AM, Rodd Leeds wrote:

Gents-

Went to clean bonding wires on a one inch thru hull and wound up turning the bolt with the nut that is coming up through the seacock base! Do you think the bolt is on the bottom of the boat, or below the glassed in backing pads Pearson has installed under each seacock? If it’s through from the bottom, I can tap the bolt with a hammer and try to knock it out the bottom– my fear is if it was glassed in under the backing plate, but inside the hull, then I don’t want to hammer it down, or I’ll put a new hole in the hull !!

Can anyone with an early 80’s boat tell me if they know how Pearson was installing these bolts? Were they put in from the bottom, counter sunk and filled, or were they put under the built up pads Pearson used which they mounted the seacock on? Not sure what to do at this point!

Thanks.

Rodd Leeds
Windseeker 1983 #214
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Rodd

I don’t know but my yard just did some work in the area around a through hull and the area. I will ask.

Thatcher A. Stone – Attorney Communication
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We replaced all of Clairebuoyant’s seacocks on the initial refit a decade ago. She is a 1981. All the seacocks were bronze Perko brand. Although they had flanges, none were through-bolted, just held in place by the screwed down through-hull fitting. No backing plates. Replaced all, as replacement as cheaper than rebuilding internal plastic parts.
We used fiberglass laminate about 1/4″ thick salvaged from a boatbuilder’s dumpster for backing plates. Some of the hull structure at the curve of the bilge was quite thin and required building up to support the through-hull fitting. Mostly I omitted bolting flanges on the new seacocks. Didn’t seem like a good idea to drill so many new holes in the boat.
To remove, I suggest you use a Moto tool with fiberglass cut off discs to cut just below the mushroom end of the through-hull fittings. Much less effort than grinding them off.
Re bonding, there seems to be multiple theories on this. I decided not to bond, except for lightning.
Quent
S/V Clairebuoyant, #132

Rodd, this link shows the proper installation of a seacock. Example 1 is ideal.
http://www.groco.net/SVC-MAN-07/Sec4/PDF/IBV-FBV-TB.pdf

Chuck

If it is the big old Groco bronze valve with the big flange on the inside of the hull. I have removed several to have the hole moved above the waterline. The bonding wire is just bolted to the flange and does not go through the hull I will send pic of one on the bench later

On a good day I can see the other side of the river!

On Apr 5, 2013, at 8:53 AM, Rodd Leeds wrote:

Rodd, if there’s no screw head on the exterior of the boat then it must be coming up from the underside of the backing plate. I can only assume its holding the backing plate to the seacock. A backing plate attached only to the seacock isn’t doing much so if its loose…

I replaced all my seacocks. I spun two with little effort. When I removed them the hole for the mushroom was oversized. Only a thin portion of the mushroom lip was securing the assembly to the hull. Any major side load to the seacock (a loose battery or a case of beer) could have pulled the mushroom through the hull as in some places its rather thin.

I set the replacements up as in diagram one. Backing plates are 3/8″ frp shaped to match the hull interior. Through bolt hardware is silicone bronze.

Chuck

Hi Chuck–
Did you use flat head bolts as in fig.1? Doesn’t look like the countersink necessary to mount them flush leaves much of a grip on the hull. Real strength would then depend on how well the backing plate is bonded to the hull. Hauling out in a couple weeks and may revisit the seacock installation.
Quent

Quent, the thru-hull penetrating hardware are countersunk phillips head machine screws.

This is the theory. The seacock is mounted to a backing plate that is thru-bolted to the hull. When installed the backing plate is bonded o the hull with 5200. In short it becomes a part of the hull. Any side load will be carried to a larger area of the hull surface. The last part of the installation is threading the mushroom up into the fixed seacock. The mushroom threads are sealed with 5200 and its snugged into place. It does not, nor is intended to secure the seacock in place.

Per ABYC it should withstand 500 lbs of side load for 30 seconds.

http://www.proboat.com/attention-to-detail-april-1-2010.html

Chuck