Thru Hull

N

Nunya

New member
I've spent several hours this winter pulling screws and potting them back in as well as doing some tabbing. Some of the screws I pulled didn't even have sealant on them. (Fresh water Pump hold down screws).Fortunately I haven't found any wet core. I just finished doing the trim tabs and there was no evidence of any leaking there. Next will be the railings on top of the cabin and handrails.

I'm wondering if the thru hull for my raw water wash down needs to be pulled and potted. Did the factory seal this area before installing the thru-hull? It is located near centerline on bottom of hull. Has anyone done this? How does it come apart?

Thanks..
 
In my 2003, the Thru hull was not properly "potted". There are two concerns-one is the water intrusion. The other is the ability to crush the core. The epoxy filler, gives a compression ring, and eliminates the potential of problems with the later.
 
thataway":qdi0l0eu said:
In my 2003, the Thru hull was not properly "potted". There are two concerns-one is the water intrusion. The other is the ability to crush the core. The epoxy filler, gives a compression ring, and eliminates the potential of problems with the later.
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I was thinking about this on my Tomcat as well. I'm sure it was not properly sealed when installed. Add this to the list for Spring prep....particularly where it's under the water line.

Of course everything else is on the back of my mind too...all rails, scuppers, windlass, Armstrong bracket (certainly bigger job to remove engines and bracket and install this correctly), etc. So far I have not moved forward on these other things but I do inspect things regularly.
 
Matt Gurnsey":1u1luosj said:
Matt-

Keep in mind that the core in the Tomcat is high density foam, not balsa.
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I've drilled through the roof and on the deck near the windlass and it was balsa. Upon inspections of my transom, via the engine rigging holes prior to my application of caulking, it was also wood.

Mine is a 2007 hull. Did they start using foam in 2008 or something?
 
Techniques may have changed, but Thataway has a foam transom core, (difficult to know the density, but I would say medium high, but not high)--the cabin top, decks, aft cabin side, cockpit floor and bottom of the hulls are Balsa.
 
thataway":40c4jhxn said:
Techniques may have changed, but Thataway has a foam transom core, (difficult to know the density, but I would say medium high, but not high)--the cabin top, decks, aft cabin side, cockpit floor and bottom of the hulls are Balsa.
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Hmm...yours was built a few months before mine. Does the foam look like wood? As in, is it tan colored, look and feel like wood?

The core in the roof and top deck were definitely balsa.
 
Matt, I assume that you are referring to the transom--the foam is a light tan color, but I used a hole saw, and the core definately was foam.
 
thataway":106rdixl said:
Matt, I assume that you are referring to the transom--the foam is a light tan color, but I used a hole saw, and the core definately was foam.
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I inspected the rigging holes pretty thoroughly before filling them with Boatlife Lifecaulk. I thought for sure they were wood....

Interestingly though....while working on my port fuel tank the other day I noticed a small plug laying in the sponson that had been drilled out. I don't know where the hole/plug was drilled but come to think of it...it was not balsa...it was foam. It was gelcoat connected to about 1/4" of what appeared to be foam. I could not separate the foam from the gelcoat I might add. I had it in hand and could not break off the foam.

Hmm...in either case thanks for the reply and Matt G perhaps I was mistaken. I have no way to check again now though. I filled the holes full with caulking!
 
It would be very unusual to put gel coat onto foam. It is possible that there was a layer of mat, then a substance called "core mat" which is 3mm thick and is used in hulls. My reference to foam was in the structural part of the transom--not sure about the higher part where the rigging goes through--I'll have to check on that.
 
thataway":37twnyb8 said:
It would be very unusual to put gel coat onto foam. It is possible that there was a layer of mat, then a substance called "core mat" which is 3mm thick and is used in hulls. My reference to foam was in the structural part of the transom--not sure about the higher part where the rigging goes through--I'll have to check on that.
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Hi Bob,
I don't follow your reference to the difference between the 'structural part vs. the higher part' where the rigging cables/hoses are drilled through. Why would there be different material in different parts of the transom?

I have attached a picture hereshowing some of my rigging holes before I added the caulking.

Thanks
 
Well with some good advice from Thataway and some elbow grease I've pulled the thru-hull, used a dremel to remove some core, filled hole with epoxy and re-drilled same. There were four SS screws holding the intake strainer on. I drilled these out and potted them also. Don't think I'll put the screws back in as the strainer is held in place by a nut in the cabin. I'll use a liberal amount of 5200 to seal strainer to hull.
I found that the strainer to hull area wasn't sealed real good. Sealant that was there was very soft. Also the four SS screws were the wrong size. The screw heads were too big to fit the recess in the strainer. I think these should be bronze screws since the strainer is bronze. I did find a little dampness on the surface of the core after removing the thru-hull. After removing some core with a dremel I got into dry material. I'm glad I went to the trouble of doing this. It would just be a matter of time before I would have had a problem.
I would recommend anyone with thru-hulls to at least check to make sure they are sealed. Better yet pull and pot them.
 
I was taking a look at the raw water intake valve on my Tomcat. On the outside there are no screws so it's just the one nut on the inside holding it together. What would be involved with removing this assembly? I did not see how I could disconnect the angled portion (there was no obvious not on the other end).

Thanks for the suggestions.
 
Matt,
Remove hose, unscrew valve from brass fitting, unscrew brass fitting, then unscrew brass nut. Thru-hull strainer can now be removed from bottom of boat.
 
Matt,
To answer your other question--yes, some parts of transoms are solid glass, some may be foam, some may be plywood, some might even have balsa core etc. Without doing testing, I cannot be sure how the Tom Cat is built.

I believe that the sides of the hull (where this thru hull is) are solid glass. If this is the case, and there is no leakage around the flanges, it would not require re-bedding. Traditionally thru hulls through solid glass are backed with blocks. I have always used teak blocks, but some people use plywood (I don't like these since they are more susceptible to rot.
 
Matt,
To answer your other question--yes, some parts of transoms are solid glass, some may be foam, some may be plywood, some might even have balsa core etc. Without doing testing, I cannot be sure how the Tom Cat is built.

I believe that the sides of the hull (where this thru hull is) are solid glass. If this is the case, and there is no leakage around the flanges, it would not require re-bedding. Traditionally thru hulls through solid glass are backed with blocks. I have always used teak blocks, but some people use plywood (I don't like plywood blocks since they are more susceptible to rot.)
 
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