maintenance for underwater thru-hulls

06Rinker270

2006 boat, what is the proper maintenance for under water thru-hull and swim platform support?  Should I put some 5200 around then?   I sanded around them for fresh bottom paint.     

aero3113

Your through hull sealant looks like it’s no longer sealing around the pickups. Best thing to do would be remove them, clean the area and reseal with 5200. If your not confident in the swim platform supports, remove the screws and reseal with 5200. Maybe even put a nice bead under the base.

Aqua_Aura

Best way to seal is 5200 UNDER the thru hull then tighten it back down. Sealant just around it won't do much if anything. 

reneechris14

The swim platform brackets are notorious for letting water in. I would back out the screws and reseal.

Liberty44140

I re did my swim platform mounts below the waterline. Removed and drilled out wider, the core was dry but I still let it air out for a couple weeks anyway, then I filled with west system epoxy, re drilled and re mounted with 4000 or 4200, whichever is ok below the waterline. Not 5200. I did sand down to gelcoat under the mount so that the sealant sealed to gelcoat and not paint. I don’t have anything against 5200 but I prefer not to use it unless I have to, 4000 or 4200 is completely acceptable below the waterline. 

rasbury

I don't understand how water can work its way through a screw...I'm going to re seal my Genny thru Hull today if I can get to it...I redid my transom and was good but now have a pretty good leak going again. Sure hard to see water intrusion, especially after everything gets wet...

06Rinker270

Thanks everyone.  I thought that would be the thing to do.  I’m guessing I should replace the screws at this time?

aero3113

rasbury said:

I don't understand how water can work its way through a screw...I'm going to re seal my Genny thru Hull today if I can get to it...I redid my transom and was good but now have a pretty good leak going again. Sure hard to see water intrusion, especially after everything gets wet...

@rasbury , with the weight of people on the swim platform it can put stress on the screws and slightly elongate/loosen the hole and sealant that was applied allowing water to seep in.

rasbury

Ah...will put those on the list I guess..so if I back out the screws and they are still nice and tight...just reseal? Are there bolts on the other side of the transom? Have never looked to be honest...and get a better look at the thru hulls...raw water was resealed but maybe I knocked it again...

aero3113

Previous boats that I’ve had were only wood screws, not nut and bolt. If your worried, take the screws all the way out and seal. If they won’t tighten up, you might have to go up a size with the screw. 

Willhound

06Rinker270 said:

Thanks everyone.  I thought that would be the thing to do.  I’m guessing I should replace the screws at this time?

If they look like they need replacing, sure. But if not rotted or heads not stripped/worn, then why bother?

06Rinker270

I’m thinking I agree @willhound. The rust does have me worried.  Should the underwater thru hulls be painted with antifouling?  Paint platform support rails and where it meets the hull?

rasbury

I would guess that anything metal should not be but that's speculation on my part. I trailer and fresh water so I don't deal with it at all...