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

[SVRocinante]

Good day all

OK, I'm not trying to be cheap here, but I just got a quote of $400 to re-bed one of my thru-hulls that is leaking (galley sink drain) add to that the bit over $500 to haul, block & launch and we're talking $900+

It's not going to kill me, but also not chump change.

Now, I don't think I can help the $500 part, but $400 seems a bit excessive to take out and re-bed a thru-hull. Is it really a 3hr job?

As best I can tell, I need to unclamp the hose, unscrew the valve, undo the nut, knock out the thru-hull; clean and reverse the process with new bedding compound or butyl tape?

Again, not bitching, just asking from those that have done it themselves in order to make an informed decision to farm it out or go the DIY route.

BTW, assuming I go the DIY route, how do I test to ensure that I did it "correctly"? i.e. I sure as heck don't want to pay an additional $500 bucks to haul the boat out again!

Thanks!

[Sailmonkey]

You've got the gist of it. I replaced three seacocks with groco flange adapters and ball valves by myself in a little over 4 hours. I would think you could do a single mushroom fitting in less than an hour if you plan ahead.

[SVRocinante]

Originally Posted by Sailmonkey

You've got the gist of it. I replaced three seacocks with groco flange adapters and ball valves by myself in a little over 4 hours. I would think you could do a single mushroom fitting in less than an hour if you plan ahead.

Much Thanks!

Any thoughts on testing? Is it even possible to test?

Thanks!

[John_Trusty]

I agree that 3 hours work is a high estimate for a single 1-inch through-hull, particularly if the outside is a mushroom and just sits on the surface (no fairing etc.) and there is no additional repair work (a simple swap out with bedding compound). To get a better idea of the job, I suggest MaineSail's excellent photo tutorial: Welcome To MarineHowTo.com Photo Gallery by Compass Marine How To at pbase.com

That said, the job can get more complex if you need to do some epoxy work such as replacing and adhering a new backing block. I assume that you're going to do this on a short-haul - just leaving the boat in the slings while the work is done, not putting it on stands?

You'll want to use a one-part polyurethane such as 3M 4000 or 4200 for bedding, not butyl which is not really rated for below waterline. A very small amount of this on the threads also works better than that silicone tape for below-waterline too. Testing? Put enough 3M stuff around the the hole and under the mushroom head - it's foolproof.

[Sailmonkey]

Originally Posted by SVRocinante

Much Thanks!

Any thoughts on testing? Is it even possible to test?

Thanks!

Testing isn't really feasible, you'll want enough 4200/5200 to smush out. Clean it up and splash the boat. If you try to skimp on the sealant you may end up with leaks......so use a little too much and deal with the mess with a roll of paper towels and some mineral spirits for the final light wipe. Do not let the mineral spirits saturate anything, just use it lightly for the final wipe.

[Suijin]

I have seen quite a few three hour thru-hull jobs, trust me. Because often what you are doing is fixing a poor prior install. That said, if it was well installed and you can wrench it out, it should go pretty quick.

If you do it properly the chances of it leaking are next to zero. I would say the critical factor is how well the new thru-hull fits the existing hole.

Make sure you change the old backing plate, assuming it's wood.

[SVRocinante]

Thanks for the link John_Trusty and for the 4200 suggestion - as you can tell, I hadn't quite gotten that far in figuring out what to do

Thanks for the additional info on sealant and cleanup Sailmonkey

Thanks Suijin - right now reinstalling existing thru-hull, at first glance it looks to be in perfect shape... pretty sure the only issue is the bedding. Of course, once it's out if I see anything to the contrary, I'll replace it. No backing plates...

All that said, now I'm a bit concerned that they might have used 5200 - have heard horror stories of how "permanent" a bond that makes!

Thanks again folks!

[SVRocinante]

Originally Posted by John_Trusty

...To get a better idea of the job, I suggest MaineSail's excellent photo tutorial: Welcome To MarineHowTo.com Photo Gallery by Compass Marine How To at pbase.com
...

Boy oh boy did you just open up a can of worms!

Unfortunately, my "thru-hulls" look like the one on the right & I'm no longer ignorant of the fact that it is not the "preferred" way to do it!

[Sailmonkey]

Originally Posted by SVRocinante

Boy oh boy did you just open up a can of worms!

Unfortunately, my "thru-hulls" look like the one on the right & I'm no longer ignorant of the fact that it is not the "preferred" way to do it!

I'll bet if you really get to looking into it your valves are lesser quality as well when compared to the groco stuff.....just gotta pick your battles at the appropriate times.

[flyingfin]

Yes, it is expensive. So is your boat sinking when you are not aboard.
Sounds like you should have them remove/replace every thru hull. Your mobilization costs for 1 thru hull is high, take advantage of your haul out and get as much submerged work done as possible!

[jamhass]

I might suggest that you at least replace the thru hull even if you do not replace the ball valve. The thru hull is the weakest part and any corrosion damage there could come back to haunt you. Also, keep the inside (exposed) portion of the thru hull as short as reasonably possible (consistent with full thread engagement in the valve). This keeps the breaking moments as low as possible.

[Ziggy]

Originally Posted by jamhass

I might suggest that you at least replace the thru hull even if you do not replace the ball valve. The thru hull is the weakest part and any corrosion damage there could come back to haunt you. Also, keep the inside (exposed) portion of the thru hull as short as reasonably possible (consistent with full thread engagement in the valve). This keeps the breaking moments as low as possible.

If you're going to haul out and take off a thru hull, you might as well replace the valve also. If there is no proper backup block, you should plann on adding one. And you might as well check all your other thru hulls and valves. Might be a good time to paint the bottom and service whatever else needs servicing too. After it's all done, $900 will seem ridiculously low.

By the way, 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.

[Badsanta]

Originally Posted by SVRocinante

Boy oh boy did you just open up a can of worms!

Unfortunately, my "thru-hulls" look like the one on the right & I'm no longer ignorant of the fact that it is not the "preferred" way to do it!

The one on the right are like mine and came from the factory like that.
The real problem is the threads are same size but different threads.
When I found the valve was only threaded on by two turns I replaced them all.
The thru hulls is a streight thread the valve thread is tapered. The valve to hose adapter is fine as it is tapered to tapered. The groco flange adapter is what's needed, the one on the left, it has straight threads on the bottom for the thru hulls and tapered on top for the valve.
You cannot have a strong connection putting a straight thread in a tapered hole or visa versa. Straight

[UNCIVILIZED]

I’d call it lucky if you can get the job done in under 3hrs, unless the system has been recently serviced, & well maintained since then. And if things haven’t, then it’s quite easy for such a job to turn into one taking several days.The reasons for which I could type a couple of pages of text listing.
Yes, in theory it’s a simple job. But, if there are any hiccups along the way it can turn into an Alice In Wonderland type misadventure.

[JerseyJoe]

Agree with Ziggy on replacing the whole setup if leaking. including installing new backing plate, flanged seacock and grounding wire(if corroded). And yes they can be time consuming if need to grind or cut out as Ziggy said.

I just did 7 of 11 of them and only one came out easy. Make sure to mark the flange on dry fit to drill for grounding wire if not already pre-drilled and that thru-hull has enough thread to accommodate both backing plate and flange or if needs to be cut.

And as Sailmonkey said go extra on the 4200/5200 to smear the external seal even though messier. Also lube the seacock prior to install even though new.

Well worth the price if done right and gives you decades of service if maintained properly.