Re-bedding a Thru-hull - how big a deal?

[Captsteve53]

Just a note on valves as some one posted above the threaded versions (which by the way usually dont comply with (ABYC H27 Compliant Connection), come in two thread formats both the same size but different in thread pitch per as:

NPT (National Pipe Thread) seals are the most popular type of seal for pressure calibration systems in the U.S. and Canada. NPT male adapters have a taper thread that wedges into the female NPT adapter. They seal due to the "out of roundness principle" which means that the male stretches the female fitting until there is so much force that the connection can hold pressure. One of the challenges with this design is that if you connect stainless steel to stainless steel then over-tightening or poor lubrication can cause gauling and damage to the threads. Thread sealant is needed to seal but only 2 turns of thread sealant is required. Any more than that and the seal can leak around the thread sealant.

BSPT (British Standard Pipe Thread) is similar to NPT except for one important difference. The angle across the flanks of threads (if you sliced the fitting in half long-ways and measured the angle from root to crest to root) is 55 degrees instead of 60 degrees as it is for NPT. Thus an NPT male will fit into a BSPT fitting or vice versa but they will not seal. This is a popular fitting in China and Japan but is very rarely used in North America unless the equipment to which it is attached was imported. Thread sealant is needed to seal the male and female fitting together.

Even many of the Groco Bronze line of valves do not have the ABYC H27 approvals so if paying the top dollar it pays to ask, nearly all of the threaded cheaper type ball valves from other suppliers such as Apollo do not meet these spec's as well.

The main difference with the cheaper bronze valves is they have additions of lead/zinc for ease of casting and machining,

[Bleemus]

I see you are in Maryland. Do you haul every season? If so perhaps using a coarse wet sandpaper around the fitting underwater then apply the stick epoxy that cures underwater around the flange. Should be enough to get you two months to your haul out and a whole winter to DIY. Just a thought.

[RickG]

SVRocinante, we are in HHN too. We had Zimmerman Marine redo all of our below water thru-hulls when we bought our B423. They bid the work fixed price and the work took longer than their estimate. The overage was driven by the extra labor to deal with the builders design - low clearance between the hull and the liner. Hopefully you have good clearance for this thru-hull.

Cheers, RickG

[Terra Nova]

OP--it sounds like you are neither qualified nor equipped to do this job yourself. You probably don't own a thru-hull fitting wrench. No shame; a man has to know his limitations. The yard is not likely going to let you do this work yourself without charging additional laydays. And it is normally a 2-man job.

Leave this to the pros. Have them replace with a proper sea cock.

[zeehag]

if you are being quoted 400 usd to rebed the damned thing why not just replace the set up and go for broke. might save your boat. prolly cost less than the allegedly simple rebedding a perhaps gonna fail thru hull. could actually save you dough and cleaning time.
good luck.

[SVRocinante]

Thanks for all the additional responses - appreciate the input!

For what it's worth, I have decided to "leave it to the pros"... this time!

[boatman1]

It's been pretty well said, and you've decided to let the yard do it, but as one more voice about boat projects, consider: one might have to fabricate a special tool to tighten the nut on the inside of the boat due to inability to get a normal wrench or channel lock pliers in the confined space in a stinkin' boats' bilge.

[skipmac]

Just replaced to 1.5" thru hulls and the seacocks on my boat. The mushrooms were in perfect condition but I could not get them out. After 30 years and probably installed with 5200 they weren't moving so had to cut the mushrooms out.

Also, many builders glass in a bronze bole that points inside the hull and secures the flange (not on yours since there is no flange) and I had to get a Fein tool and cut the threaded end of the mushroom off on the inside.

It took me over three hours just to get the old thru hulls out of the boat. After that installing the new flanges, mushrooms and seacocks was easy.

NOTE: Don't let the yard use 5200 if you will ever, ever need to remove them or work on them. 4200 is the most I would go.

[bobnlesley]

Originally Posted by Ziggy

...when I did my thru hulls, one of them was seized so tight to the valve I couldn't budge it and eventually I had to grind it out. That certainly took longer than 3 hrs.

After the first couple of seacocks that I ever replaced, I now just replace the thru-hulls too as a matter of course. Having disconnected the hose (cut it off if it's tight) I don't even bother trying to unscrew anything, just carefully apply an angle-grinder/disc-cutter to the outside flange then knock the whole unit inwards; I know that I tend to work slowly/methodically, but if the parts/tools are to hand, I'd still expect to be done and dusted within 90 minutes, provided that there's no issue with the hole itself.

[SVRocinante]

Originally Posted by boatman1

... one might have to fabricate a special tool to tighten the nut on the inside of the boat due to inability to get a normal wrench or channel lock pliers in the confined space in a stinkin' boats' bilge.

I hear you! I had already started to look at possibly using a crowfoot wrench for exactly that reason and had started to track down and price the stepped wrench for the outside when I decided it just wasn't worth it at this time... other priorities!

[SVRocinante]

Originally Posted by skipmac

...NOTE: Don't let the yard use 5200 if you will ever, ever need to remove them or work on them. 4200 is the most I would go.

Thanks!

[Bleemus]

Good advice. The only place I would use 5200 on a boat is the keel hull joint.

[Djarraluda]

Just to be radical, I will note you refer to the sink drain.
Sink drains should be on the waterline, semi submerged at best, so....
On a day when your dock neighbour is away, or if you have adequate space for the dinghy anyway. Heel the boat over by loading gear one side, hang on end of boom, take main halyard to the dock and winch. Now the through hull is some 6 inches above the waterline and you can work happily.
Most professionals just remove skin fittings with an angle grinder, cut off the flange and push in. Clean up and bed a new skin fitting, you need an assistant to hold it whilst you do the clamp nut inside. I would make a large flange out of G10 or similar before hand and bed this behind the flange nut as well (so we get Mushroom, bedding, Hull, bedding, G10, bedding, nut.
Fit new sea cock/ball valve whilst someone is outside to assist in holding, as you do not want to rotate the skin fitting and break the bedding compound.
When all set, level the boat out and you are done.
Roger

[Suijin]

I use 5200 on thru hulls. Damn straight. Yes it takes an extra 10 minutes to get them out but I love the stuff.

And step wrenches are over rated and in my opinion, largely useless. They never seem to fit well or allow you to apply a good amount of torque. I just jam the handle of a crescent wrench in and put another on it to turn it. Far more leverage to twist them out.

I don't have tri-bolted flanged thru hulls on my boat, but the glass is over 1" thick where all of them are situated. That said, I might go for them in the engine compartment. All the others are in areas where there is nothing heavy and no risk of stepping on them or otherwise impacting them. I don't like the idea of drilling three MORE holes in the boat to support one hole. I get why RC advises them but I think they are overkill for lots of applications.

[Bleemus]

Or you can do the countersunk version into the G10 that eliminates the three extra holes.