Raw water intake

[theogonzalez]

I have old gate valves for my raw water intakes. starboard side will not close. I know i need to replace both gate valves with ball valves. Any idea on how hard it is to remove (unscrew) the gate calves from the raw water scupper? any tricks?

[mike ohlstein]

Heat gun and leverage..... Gigantic aluminum pipe wrench(s). Two person job, with one in the boat and one underneath. You might have to pull the deck if the access hatches aren't big enough.Replace with FULL FLOW flanged seacocks. Bed in 3M 4200 (not 5200) or Sikaflex 291. If it was my boat, I would use a (roughly) 6X6 piece of 1/2" marine plywood (encased in epoxy or polyester resin) for a backing plate and thru bolt to the hull. Expect to pay $600 each for 1.5" valves. If you're looking at something cheaper, you're probably looking at the wrong thing.

This is also the perfect time to add crash valves. The safety factor can't be overstated and the ease of winterization is worth every penny, especially if you're a DIY guy. If you choose to add crash valves, make sure that you use LONG SWEEP brass elbows. No hard 90 degree turns.

[PeterPalmieri]

To further Mikes comment both dreamgreen.org and Groco make composite backing plates if you replace the thru hulls.

[Carl]

If you do not care about saving the fittings and good with a grinder n sawzall, cut the intake scoop flush to hull, go inside and pull/pry the valve out. The same can be done from inside...but inside tends to be tighter to maneuver and makes a good mess.

[Rawleigh]

I have Graco full flow ball valve seacock with the crash pump option built into the valve. They also make a crash valve inlet you can add on top of an existing valve.

[mike ohlstein]

I don't know enough about the composite backing plates, but a 'solid' backing plate isn't advisable for a thru-hull. You want it to give. You want it to conform to the shape of the two surfaces. The marine ply will last for 35 years. That's probably long enough......