Big is good - do not even waste the effort of a blink at installing a larger thru-hull. And just because you removed a 1.25" thru-hull does not mean that the new Groco thru-hull will fit! Last year I replaced my boat's nine Groco knock-off rubber plug
sea cocks and their thru-hulls, ranging from 0.75" to 1.5", with the Real Deal, and the new Groco thru-hulls did not fit the existing flush molded-in holes.
Here are pictures and commentary from my galley
sink thru-hull, which is 1.25". Although I retained the 1.25" hose fitting because that is what is on my galley
sinks, it is the same process to install a larger thru-hull or use a full-flow hose adapter.
Galley sea cock - the beginning:
After tapping through the very difficult to remove thru-hull - note the detached epoxy
barrier coat (gray).
molded-in for the thruhull.
The new Groco thru-hull did not fit the old 1.25" hole - I inserted the thru-hull and drew a line around it with an indelible marker.
I used a hammer and common wood chisel to tap . tap . tap away the fiberglass
until the new Groco thru-hull fit flush.
I followed instructions from a (then) recent issue of Professional Boatbuilder
to install the new seacocks and thru-hulls.
After bottom paint
Inside - note that I did not slather the entire sea cock with sealant
where it mates with the backing plate - only where the mounting bolts are.
My reasoning for this is that if the thru-hull leaks
I want to know about that - so if water
is getting through between the thruhull and hull
, it should seep out between the seacock and backing plate - the bolts into the backing plate are isolated from the leak with sealant
- protecting the backing plate wood from rot
DO NOT USE 5200 - we all want these installations to be permanent, but if there is a leak you need to remove the mess and fix it! 5200 makes this a *difficult* thing to do.
My bilge pump
thruhull was 0.75", but when I removed it from the hull the fiberglass was shattered around the thruhull from hitting a dock
or something, and it was very easy to chip out the broken fiberglass to size the hole flush for a 1" thru-hull. I installed a Groco Full-Flow hose adaptor on the ball valve, which meant that I could use a 1.25" hose from the bilge pump
- no problemo whatsoever.
Do not hesitate to call Groco with your questions - ask for Patrick - he has been working there since Groco made the ruber plug
seacocks, and can answer any of your questions.