Conversion To Keel Cooling Engine From Freshwater

[stefano_ita]

Hi all

I was wondering, in order to avoid another hole under the waterline, how to convert a ordinary freshwatercooled via heat exchanger to keel cooling.

I mean in a used boat with fiberglass hull.

I thought about cut a square between the ribs of the hull, replace it with a sheet of aluminium, that goes bigger then the hole, laminate it with fiberglass for a pair of inch on all the 4 side, both exterior at the hull, both interior, and on that aluminium sheet add the aluminium box (smaller, to let alluminium dissipate heat and do not overheat the fiberglass around )

Any idea also how to delete all the holes under the waterline?

I thought toilet all to a black water tank with macerating pump and reversed U at the stern so no bad small, bilge pump is ok; for raw water sink and watermaker a small pump that can lift water, placed at stern with the same reverse U shaped plastic pipe with a small "buffer" tank.

Both the pipe at stern laminated to the hull for estetic reason

Any advice?
Thanks
Stefano

[Perstarebob]

It is very common in commercial boats to have keel cooling via a purchased keel cooler or a piece of pipe fastened to the under water . You will still have a thru hull for water to cool the exhaust unless you fit a dry exhaust which may be difficult in a pleasure boat.
On several of my boats I placed waste discharge for sinks above the water line . A 49 foot boat that I once purchased had nineteen underwater thru-hulls , on first haulout I reduced to six .

[stefano_ita]

Thanks
I also thought about it but 2 holes, one outpout, one inpout, plus keep it clean, ensure it to the fiberglass hull along the pipe...doesn't like it...

No problem for dry exhaust, i thought to keep the original engine, but get the raw water circuit close... (except 2 Y valve as to use the raw water pump as bilge pump with inpout as bilge and oupout outside in case of emergency)

The hot water exit from exhaust manifold in stead of go into the exhaust pipe go to the heat exchanger...

I mean like 80 x 80 cm aluminium with 70x70 cm heat exchanger welded to it, so the 10 cm (5 inch) free, just aluminium works as buffer to do not overheat and ruin the fiberglass...

Does epoxy resin and fiberglass glue well to aluminium??

LOL it was a pasta colander!

[a64pilot]

Better to fit a water closet I think they may be called.
Think bonding a 12" pipe that extends above water line and have your thru hull in it. You can knock off a thru hull and pipe just fills up to waterline. No water in the boat.


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[stefano_ita]

Originally Posted by a64pilot

Better to fit a water closet I think they may be called.
Think bonding a 12" pipe that extends above water line and have your thru hull in it. You can knock off a thru hull and pipe just fills up to waterline. No water in the boat.


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Thanks didn't thought about it

Mmh, the only problem could be the ordinary plastic bag that close it due the vacum(known a person who burned the engine for it...but waited 3 minutes to react from the alarm)

How much can lift an ordinary raw water pump? Primed obviously, i guess with the half U toward the engine always empy and when i turn engine off the pipe toward the sea get's empy...could this be a problem or when i re turn on the engine, the water vacummed will vacum more water, lifting it from the sea leven, overtake the U and go to the engine, and going on as usually...

Thanks

[Lepke]

Properly plumbed and maintained thru hulls are not a problem. In fifty years, all the damage, fitting failure, sinkings I have seen were due to improper plumbing, lack of maintenance and outright stupidity.
Keel coolers have at least one thru the hull. They cause drag, need a zinc - causing more drag, can cause a boat to pull to one side. In a grounding the cooler can be damaged, leak or worse yet rip out the thru hull. They require additional maintenance. Marine growth can cause lack of heat transfer. I would think on a sail boat where you don't have much speed anyway it would be beneficial to add drag.
I have an old boat with several thru hulls that are unused. They have wood plugs driven from the outside and capped on the inside. Just because you have a phobia of thru hulls doesn't mean a future owner will. What you are proposing will hurt the value of your boat.

[stefano_ita]

Thanks

Sorry i guess i wrote it wrong...i'd meant Skin cooled, where the heat is dissipate via the hull itself, not as external radiator..

Keel Cooling Calculations - Beta Marine