SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Notes on a thru-hull replacement

9.6K views 20 replies 10 participants last post by  WoobaGooba  
#1 ·
This little Catalina 22 is my first boat, and for my first project I replaced the 40-year-old garden hose valve they glassed directly to the hull with a proper seacock, following Maine Sail's instructions.

It is probably overkill to upsize from 3/4" to 1" and go all bronze on a little boat that's being sailed on a little lake, but I want to learn how to do things The Right Way.

So yes, my first boat project involved drilling a new hole in the boat and plugging an old one. Both sink-the-boat propositions.

Before:
Image


After:
Image


Other that the slight kink in the one hose because the bend radius is a bit tight, I'm quite happy with the results.

Things I have learned:

A) Apparently I have a wimpy drill press, because I burned out the motor using a 6" hole saw to cut the backing plate from G10. Ohmygod that G10 stuff is crazy hard. I had to finish the cut with my hand drill. I think if I were to do it again I would cut an octagon with my table saw.

B) Working with epoxy is fun! That stuff is great. And so simple. I was intimidated, especially since these are both below-the-waterline, but I feel very good about the results. Oh, except it's not fun when you're on your back working where you can barely reach because the swing keel is blocking you and also the epoxy is rapidly hardening because 8 pumps was probably too big a batch. Yes, I have epoxy in my hair.

C) Sikaflex 291 is amazingly resistant to removal. It's everywhere and it won't go away. It's the herpes of boat products.

Anyway, boat goes in Friday, I'll report back if my repairs are actually watertight.
 
#8 ·
Yeah, wtf? My hull is about 3/8" thick at that point and is much, much softer than the 3/8" G10 that I reinforced it with. Given the strength of the G10 I probably tripled the strength of my hull for those six inches. I wonder if that's too much.

Slow speed, yeah, I geared down my drill press to it's slowest setting, but it still burned out the motor. I was paying too much attention to how hot the G10 and the hole saw were getting, I didn't realize the motor was frying pan hot.
 
#7 ·
I confess, I went Home Depot for the hose.

I think I'll order some good reinforced hose online, but I'm going to wait till I put the boat in the water. Given the height of all that bronze and the very shallow nature of a Catalina 22, the hose might be above the waterline.
 
#9 ·
For G-10 and other sheets of fiberglass I use a Jig Saw. Lots of different blades available including carbide tipped. If I wobble a bit on the circle part - I use a small bench / belt sander to even things up. I also knock the sharp edges off to protect my fingers.

I also use Marlon fittings to stay away from the electrolysis, a friend had a bonding problem but did not know it, went to change a bronze fitting and it fell off in his hand (yes the boat was in the water) - yes he had some excitement for a few minutes

His boat was in salt water
 
#11 ·
Put a groundwire/strap on the Thru-Hull

flange, and you shouldn't have any issues with rapid excess electrolysis.

DrB
 
#13 ·
Hah!

I think I'm past sticker shock. When you count the new tools I had to buy, the epoxy stuff, the burnt out drill press motor... That is one expensive hole in my boat.
 
#16 ·
Is it *always* above the waterline? With any load on the boat? Any angle of heel? If the far end came loose, could it ever drop below the waterline and siphon water in?

I'd spend the extra 0.1% of the total job cost on the fancy hose and call it good. Don't forget the AWAB clamps...
 
#17 ·
Maybe if I got five or six people to stand right at the back of the boat it might pull the hose below the waterline. It's centerline, so heel wouldn't do it.

But you're right, I'd hate for it to rot and drop down and somehow get a siphon started. Another $15 to get three feet of Trident is really nothing.

(Yes, I double-clamped with stainless non-perforated hose clamps :) )
 
#18 ·
That's called "boat math", my friend. Now that you've graduated from 101, you can start studying for 201. That's where you convince yourself that you really should get a spare 3' of Trident, plus spare clamps and (you can't be too prepared) a backup seacock "just in case".
 
#19 ·
I did get extra hose clamps just in case, and now that you mention it the long-term plan is to connect the sink into this thru-hull, so I'd probably better get AT LEAST three extra feet of trident. Probably need new fitting for the sink too, and another seacock so I can shut the sink off separately. I might as well order it all now. Hmmm, another $100 and I can get free shipping. Maybe I need a fishfinder.

$$$ :) $$$