Originally Posted by noelex 77
Yes good point. I have standpipes on my boat leading above the waterline.
It's worth considering other openings. My boat has a watertight box around the rudder
that leads above the waterline.
This still leaves the exit of main shaft which is difficult to make foolproof. In my boat it is at least separated so it would only flood a small part of the boat. We would not sink, but the engine
would suffer some water damage.
These ideas are worth incorporating into a custom boat, but they are very difficult to retrofit.
I think the OP's concern is absolutely valid. Through-hulls frighten me, too.
My boat has caissons around the rudder
(like Noelex's) and around the bow thruster. But she has 15 (!) through hulls for all kinds of things including deck
drains (which seems crazy to me).
The perfect solution to this is Dashew's -- all through-hulls concentrated in forepeak and engine
room, both of which are isolated from main passenger space by watertight bulkheads. Nice, eh? That's the smartest solution I ever heard. If you have a breach, the boat won't sink.
Standpipes and sea chests are fine, but I'm not sure that one big hole in the bottom of the boat is so much better than several small ones. The main advantage is that they are harder to clog.
To the OP: your "overboard radiator" is a common solution -- it's called a keel cooler
. Works great on metal boats; rather harder on plastic ones. But that leaves you with the necessity of rigging
a dry stack exhaust
, which is really undesirable on a plastic boat. The great thing about cooling your engine with sea water is you dump the sea water into the exhaust
to cool that down enough to use an ordinary hose to convey the exhaust gasses out the transom.
Concerning clogging: I have just installed redundant means to detect a cooling water clog. This after I had a lot of problems with my generator
last year following a weed-clogged cooling water intake. I have put temperature sensors on both raw water
pumps. An alarm
goes off over the N2K network if the temperature exceeds 30C. The raw water
pumps are themselves water cooled, and start to warm up if there is a compromise of cooling flow. Besides that, I have installed exhaust temperature alarms -- simple, cheap
, freestanding ones -- on the exhaust elbows of both engine and genset.
If you catch a cooling water flow problem early enough, you can shut down and unclog before damage is done. I don't worry as much about an overheated engine or genset -- we all have alarms and/or shutdown devices for that. The nightmare scenario is a burned-through exhaust hose, which can cause a fire, flooding, or other serious problems. My engine room is sealed, soundproofed, and forced-air ventilated out the transom, so I would never smell a burning exhaust hose in time.