Washdown Thru-hull

[fliboi21]

Putting in a new washdown pump this weekend with new thru hull. I've read all the past project threads on this and got some great info. The only question I have left is how long does the stem need to be for the scoop thru-hull? I'm assuming the hull is somewhere around an 1" to 1 1/2" in the area I want to mount. What lenght have you guys used? I was also going to use a 3/4 diameter thru hull to match the intake on the washdown any pro's and con's on size. Thanks in advance.

 

[DaleH]

I was also going to use a 3/4 diameter thru hull to match the intake on the washdown any pro's and con's on size. Thanks in advance.

Yes, 1st - for the safety of you and the boat - you really should put a seacock that can CLOSE between the scoop pickup and the pump. On my install, vintage '92, the scoop post was long enough so that the bronze seacock screwed onto it seats against the hull, with full thread engagement. 3M 5200 all around ...

~$50 for bronze or marlon (Forespar) Never, ever put a thru-hull in below the waterline without a seacock :shock: !

 

[Sleigher]

Here is a web site that I came across when I installed my thru-hull pick up for my cooling loop. http://www.pbase.com/mainecruising/boat_projects
The hull wasn't nearly as thick as I thought it was going to be.
I ended up making a backing plate out of 3/4 inch fiberglass which I then glassed into the hull.

Good luck,

Peter