Washdown pump water source

[Archis]

I found a brand new washdown pump on my boat and have an installation question.

I have two possible sources for the seawater, the yanmar heat exchanger loop and the head seacock. Tapping into the HE loop is way more convienent, but I'm not sure if this is a good practice. Is tapping in the Yanmar HE loop a good practice?

Thanks

P.S. There currently is no washdown pump installed on the boat.

[TrueBlue]

We have a PAR seawater belt-driven pump with a dedicated through-hull which serves both the galley tap, aft deck and foredeck hose outlets. It's my opinion that your washdown pump should have it's own dedicated through-hull and valve. Doubling up with the HE hose or head through-hull is just asking for trouble.

If it's not worth doing right - don't do it.

[Archis]

How much does it cost to add a new through-hull?

I'm not sure I like putting another hole in the bottom of my boat, it seems like yet another point of failure.

[TrueBlue]

I suppose since my boat has 14 bronze seacocks and through-hulls, I would be the wrong guy to ask about minimizing hull penetrations. Costs will vary - depending upon who does the work of course. It's not that difficult, if you're already on the hard.

Don Casey has a good article for DIYers and an interesting viewpoint regarding through-hulls - counter to my suggestion - Installing a Seacock

Jamestown Distributors sells a Groco 3/4" flange base seacock for $110. and the Groco Thru-Hull Fittings - Bronze, NPS at $10.89.

[camaraderie]

Use a T on the head intake seacock. No problem with that at all. Don't mess with the HE loop...needs to be dedicated.

[sailingdog]

You can cause a lot of cooling system problems if you tap the line into the HE line. The head is a much safer place to tap into, and doesn't endanger the boat by doing so.

[Archis]

Thanks, that's kind of what I figured.

[Archis]

I have a couple of questions now about installing the hose thru-hull for the pump output.

1) Is there a common location for mounting the hose attachment thru-hull? I'd like to find a location mid-ship so I could get by with a 25' hose on a 33' boat, but I want to keep the deck clear of things to trip over.

2) I'm not clear on how to drill the hole for the thru-hull. First should I over drill and fill with epoxy and then drill again?

3) Can I use a spade bit to drill through the fiberglass or should I use a hole saw? A spade bit seems like a bad idea, but I figured I better ask.

[TrueBlue]

Following is an excerpt from the Don Casey article I linked in the above post:

The instructions that follow assume that the boat is out of the water. A helper will be needed.
New Through-Hull
Installing a new through-hull fitting necessitates a new hole in the hull. Always locate seacocks where they are readily accessible or you defeat the purpose of having a valve in the line. Before you drill the hole, double-check the location carefully both inside and outside the hull to make sure, for example, that inside there will be ample room to throw the handle, and outside the new fitting is not going to set up turbulence in front of your depth sounder or speed log impeller. From inside the hull, drill a small pilot hole and check the location one more time.
Select a hole saw the size of the fitting you are installing and cut the required hole by first drilling from the outside of the hull until the pilot drill in the hole saw penetrates the hull, then finish the hole by drilling from the inside. Clean up the edges of the hole with emery cloth. If the hull is cored, dig out the core around the hole to hollow an area at least as large as the flange of the seacock you are installing. Fill the hollow area with epoxy putty and allow it to fully harden before proceeding. The epoxy provides a solid base for the through-hull and prevents water from reaching the core material.

In the past, I have used two types of hole saws for through-hulls. Do not use your spade bit. Whether using a fixed diameter saw, or adjustable, the hole should be slightly larger than the fitting OD. My adjustable tool is invaluable for cutting mutiple diameter holes, and is what I usually prefer when working with FRP and sheet stock :



The location of your deck hose outlet can be placed anywhere you feel to be convenient. My boat has two, one at the bow for anchor mess clean-up and the other just under the cowling, on the aft deck helm console of my pilothouse. Both fittings are stainless and fitted with screw caps to keep the line pressurized when using the galley tap and to keep debris and unwanted water out of the line. I also use seawater for washing my teak decks.

[sailingdog]

Hey TB-

Where'd you get the adjustable hole saw??