Holes In Boats.......?

[Seafever]

Looking around the boat dealers and boatlots I notice on many new fiberglass hulls that there are holes below the waterline on many models. These are outboard propelled boats. Seen it on new Campions too.

I know you need bilge-pump holes and the like......but why put a hole of any kind below the water line?

(Washdown pump maybe?)

Isn't any hole below the water line asking for trouble eventually?

Noticed on some older inboards the exhaust outlets are damn near underwater too...with just a rubber flap keeping the water out. Doesn't make sense to me.....

What do you think?

 

[scott craven]

All of the holes would have check valves in line...
problem is they can fail.
I would not want any drillings below the water line.

 

[wolf]

Toilets and wash down pumps more than likly and yes they will ... well "should" have brass shut off valves on them and any others on a boat I have them on mine. kinda need it for a potty LOL

 

[Rockfish]

Most larger sport boats (over about 19 feet) have through hulls both below and at or very close to the waterline plus others higher up on the hull. They are there for a number of reasons and some of those may be capped (no longer in use). Those below or close to the waterline that are not capped will have a seacock (valve).

Those below the water line can be for head intakes, inboard motor cooling, wash down pumps etc. Those on the waterline or close to it and just as risky in my opinion may be there for things such as used water outflow (head/macerator outflow, possibly gray water etc). Those higher up on the hull are for bilge pump outflows, sinks, gas tank vents etc.
All of them, both capped, and active with seacocks require regular inspections, maintenance, lubrication and periodic replacement or rebedding. Seacocks need to be exercised to keep them working well or they can freeze up. Lubrication liquid should be added to your head outflow water periodically.

This summer I had 3 through hulls replaced and two seacocks. The through hull for the washdown pump was replaced but I just had it capped. I can put a new seacock on it in the future if I decide I just can’t live without it, but for now it is one less below waterline valve that could fail. I may rig up a system where I can put a dip tube over the side to provide water to the washdown pump without using the through hull and seacock.

Good quality bronze (not brass) through hulls and seacocks are expensive but it is the survival of your boat and those aboard we are talking about. My boat is glass, I understand it is different for Aluminum boats.
I did a fair bit of research on this. The sea side of the bronze through hull should have a rich chocolate brown patina on it and be smooth after a little use. If there is a gritty surface and/or sparkly specks, the alloy may have contaminates in it such as zinc. Not a good thing. Spend the money for a good quality name brand.