Tech Tip#29 Removing Old Thru-Hulls

Currently our plumbing students are learning about thru-hulls, sea-valves, and potable water systems. We put this video together showing many different strategies for removing old thru-hulls. Students were learning, on King's Pride, that taking out the old is usually much more difficult than installing the new! Enjoy
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Michael Beemer
Skagit Valley College
Marine Technology Department Chair
[e-mail]

[@MarkLah]

Excellent tips - surprised your videos don't get more hits, especially coming from a reputable source. There needs to more content exactly like this for the great good of the sailing/cruising/boating community. Keep it up!

[@SVCSkallywags]

More to come!

[@SVCSkallywags]

Still getting views, and putting out content. Hard to film, and teach full time- but we enjoy it, training technicians all the time 😁✅

[@JohnnyLawBMC]

Another great video. I truly appreciate you taking the time to make these. They are priceless.

[@SVCSkallywags]

Thank you very much!

[@loyalegan9501]

Great video and tips!

[@captainkrunch6372]

How tight does the nut need to be, also how much of the old sealant need to be removed, will fresh sealant adhere to some of the old sealant that you can't get off.

[@SVCSkallywags]

I suspect new sealant would adhere, but I've always been able to get the old cleaned up - a good sharp chisel works well. When re-installing a thru-hull the nut just needs to be snug, once the adhesive/sealant curses....it's a done deal

[@agusus]

I know this is an old video but one question - you said you wouldn't use a Fein multitool to cut off the thruhull head (too much risk of damaging gelcoat), but would you use an angle grinder? I see some folks doing that (ex, Sailing Sunday installing TruDesign valves). I have a Fein oscillating tool but have never used a grinder. Are they easier to control? Seems risky to me but not sure since never used one.
I have a 2" thru-hull to remove so it may be hard finding a step bit large enough, and big hole saws can sometimes bind up.

[@SVCSkallywags]

2" you won't find a step bit, my guess. Hole saw works just fine. Bronze is soft if you get a plug in, and find the center, hole saw is fast and easy. I've seen success with vibrating tools as well.

[@sszczerb1]

Look at all those tools on that boat!! What kind of tips and tricks do you have prevent them from corroding and rusting?!

[@SVCSkallywags]

Good corrosion block like Corrosion-X or LSP3

[@Sailingintoinfinity]

2 questions: 1) what’s the purpose of hammering a piece of wood into the thru hull before cutting off the mushroom head with a fien tool? 2) is it really a big no no to thread the thru hull into the seacock from the outside while holding the seacock on the inside steady? What if you’re unable to thread the seacock onto the thru hull due to access for instance a bulkhead nearby or lack of space on the inside?

[@SVCSkallywags]

The wood is if you are using a hole-saw to remove the head [need a place for the pilot bit]. We don't use fien type multi-tools on the exterior of a vessel as it can damage the gel-coat. Thanks for asking!

[@agusus]

I can't believe how many people use 5200 on thruhulls. 4200 would be fine.

[@SVCSkallywags]

Yes, 5200 is a bugger, but strong. Many boaters just want it. One of my staff HATES it and will not use. Usually destroys the boat when trying to remove...