SailNet Community banner
1 - 14 of 14 Posts

·
Registered
Joined
·
45 Posts
Discussion Starter · #1 ·
While I wait to see how the whole wiring bit gets sorted out, I figured I might as well get started on my other projects.

Although my 35y old OEM gate valves are all in great shape, at haulout I noticed that my engine intake thru hull was spinning on the locknut. The original plan was to remove/clean/seal/reinstall but I figure now's as good a time as any to start replacing.

Plan is to tackle 2 per year and replace with groco flanged adapters and ball valves, as per the compass marine how-to.

Question 1: some of my existing thru hulls are 1/2". Groco's smallest adapters are 3/4". What's the easiest way to bore out the existing hole? I was thinking of plugging with wood/epoxy to give me something to drill a pilot hole into. Any other options?

Question 2: G10/fiberglass board seems to be the gold standard for backing plates. Since this stuff sounds like a real pleasure to work with, I'm looking into the pre-made backing boards by Groco (Groco BB-1). Has anyone used these? Thoughts? Seems like I can simply epoxy these in place and install the seacock/flange with bolts from inside the hull. Am I missing something?

cheers,
Novic
 

·
Registered
Joined
·
137 Posts
Quite a bit depends on what type of valves you are using. If you want bronze, consider the one with the integral flange for attaching to the hull/backing plate. Perko Seacock You can also get a separate flange that screws onto your choice of valves. Or, you can use Marelon like I have on my past three boats.

The best way to enlarge the hole is to remove your existing valve, prepare the surface inside the hull, glass a suitably sized (3-4") marine ply block in place and then use a hole saw to drill into the block. The pilot bit will enter the block before the hole saw touches the hull and you end up with a new clean hole.

Make sure you use double clamps on all hoses.

Murph

S/V Amalia
1965 Cal 30
Muskegon, MI

Starting the Great Loop in 2015
 

·
Daniel - Norsea 27
Joined
·
1,256 Posts
Definately don't want to reuse the old valves.

I've replaced one with a Groco seacock so far for the raw water intake as it was quite loose too. I also used the Compass Marine site that Maine Sail so kindly provides for us all to use.

Once you get the prep work and start installing, it's really not that hard to do.

The method CaptainMurph mentioned for drilling out the hole is the same way I drilled a hole on deck that was at a different angle than the deck surface (used for an air vent) and it worked out quite well. If not glassing it in place, maybe screw it down just enough so it won't move, then fill in the screw holes with epoxy. If the surface is curved, then glassing (or another way) would work well.

Anyway, just make sure you read over the instructions to make sure you understand the steps so once you actually install your seacocks, you'll have no problem with them. I still have about 7 more to go to replace the others (maybe glass one over altogether).

Best of luck to you on this project.
 

·
Registered
Joined
·
678 Posts
Question 1: some of my existing thru hulls are 1/2". Groco's smallest adapters are 3/4". What's the easiest way to bore out the existing hole? I was thinking of plugging with wood/epoxy to give me something to drill a pilot hole into. Any other options?

Question 2: G10/fiberglass board seems to be the gold standard for backing plates. Since this stuff sounds like a real pleasure to work with, I'm looking into the pre-made backing boards by Groco (Groco BB-1). Has anyone used these? Thoughts? Seems like I can simply epoxy these in place and install the seacock/flange with bolts from inside the hull. Am I missing something?

cheers,
Novic
So you want to drill a larger hole where there already is a hole.
1. Get a 5/8" hole saw and drill into a piece of 3/4" plywood. You'll be left w/ a wood plug that is pretty close to 1/2" in dia.
2. take a 1/4" carriage bolt and insert it into the hole left in the plywood plug you just drilled and fasten it in place w/ a nut on the back side.
3. Now insert the bolt into the arbor of a 3/4" hole saw instead of using the 1/4" bit you normally would.
4. leave about 3/8" of an inch of the wood plug sticking out of the hole saw so you can insert it into the existing hole.
5. Drill your new, larger hole! If for some reason you don't feel the wood plug fits snug enough, wrap some tape around it to build it up in diameter.
I may have pics showing this on my computer at home. I'll look.

I highly recommend G10 although it's a b1tch to cut. I used bimetal sabersaw blades or sometimes bimetal hacksaw blades.
 

·
Registered
Joined
·
541 Posts
...I'm looking into the pre-made backing boards by Groco (Groco BB-1). Has anyone used these? Thoughts? Seems like I can simply epoxy these in place and install the seacock/flange with bolts from inside the hull. Am I missing something?

cheers,
Novic
You can install the seacock/flange from inside the boat , but you still need to be careful about the thru-hull, as it will be screwed into the flange from the outside, tight with the hull. As per MS instructions, be careful when you dry fit to make sure the handle is oriented as required.
Also, get a step wrench (expensive stuff!). The only reasonable priced one is sold by Hamilton Marine in Maine.

The Groco plates are the easiest way to go....
My take on this is that the purpose of the backing plate is to spread the load of the flange. I would say to accomplish this one would need at least 1/2 to 3/4 inch over the radius of the flange. The backing plates sold by Groco is the same size as the flange, so not sure if it would serve any other purpose as to increase the thickness of the hull to permit a tighter fit between the thru-hull and seacock...
Making ones with bi-axial tape and cloth as per MS instructions (again) seems like an easy alternative to paying the $40 or so for each plate. My 2 cents.
 

·
Registered
Joined
·
2,960 Posts
Also, get a step wrench (expensive stuff!). The only reasonable priced one is sold by Hamilton Marine in Maine.
[Or, it is much cheaper to make necessary step wrenches. Use a Dremel tool with cutting wheel to put slots in an appropriately sized socket wrench head. Real easy to do and works very well.
I sure someone is going to tell me why this is a terrible idea, but…

I just went through my tools and found a Crescent wrench whose handle was the right size. I put the handle up there, then put another Crescent wrench on the handle of the first one. Not as slick as having a dedicated tool, but it worked well. I got Sikaflex all over the wrench, but that just give it a nice well-used look.
 

·
Registered
Joined
·
45 Posts
Discussion Starter · #13 ·
Thanks for all the awesome tips.
SailorDave, your method of hole-enlarging sound very elegant, and I'll have to give it a go if I have the right parts on hand. Otherwise I'll probably go with the "pound in a wooden plug" method.

Hadn't even thought of the step wrench. I'll probably end up buying one, as I have another 7 thru hulls to replace after this. Buck Algonquin appears to have a reasonably priced one that I can get locally.

SVTatia, I agree that the groco plates aren't as large as I'd like, but I think I'm willing to make that trade off for the ease of installation. As I seem to have >3/4" solid glass in the thru hull locations, I think the installation will be plenty solid, even will the smaller plate.

cheers,
Novic
 

·
Daniel - Norsea 27
Joined
·
1,256 Posts
Hadn't even thought of the step wrench. I'll probably end up buying one, as I have another 7 thru hulls to replace after this. Buck Algonquin appears to have a reasonably priced one that I can get locally.

cheers,
Novic
I got a step wrench for the same reason. I got a bunch of them I'll need to replace. It's actually a useful item and if you upgrade to other boats, you could end up using it some more.:rolleyes:
 
1 - 14 of 14 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top