Through hulls on passagemakers ???

Why not make a part of the boat into a cooler, rudder blade, keel etc

 

Thanks guys. Due to the price of steel, we are looking now into a refit of two different boats. One is keel cooled already, and the other we are still gathering info on. It is a 61 foot plank displacement. Both of these boats are livable and would offer the opportunity of a gradual refit. I will be mostly in the gulf and will be running less than 200 hp., as do most of the keel cooled shrimpers. What negative effect would the warm gulf and tropical waters have on keel cooling. Would the sizing or materials be different than one designed for PNW ?

 

"Would the sizing or materials be different than one designed for PNW ?"

NO!

Keel cooling is designed/built for worst case , fouled cooler in 95 deg tropic water , engine at full load., vessel stopped.

A simple thermostat device in the keel cooler supply and return circuits (about $500 ) allows the temperature of the return water to go back to the engine at the proper temperature (usually about 160F).

This avoids over cooling and extends engine life.

FF

 

That is what i had hoped, I just had to ask because of a comment Tad made about his cooler working good in the PNW. I guess i probably read into his statement that their could be a difference. Thanks Fred!!

 

I've had good luck here in the PNW using as a rule of thumb .333 sq ft per brake HP for steel and .167 sq ft per brake HP for aluminum. This is about 20% more than is recommended as minimum by some engine makers. But we have cool water temps and good current/tidal flow.

I've heard of keel-cooler problems in some areas of Australia. It seems the live-aboards were anchoring in what sounded like shallow water lagoons. Small to non-existent tides (stagnant water) and high water temps lead to overheating when charging batteries at anchor. The answer was heat exchangers, which apparently solved the problem.

 

A heat exchanger is simple enough. Is your steel/alum differential based on average weight of vessels and torque required, or based on using the induction characteristics of the metal in some way. Copper tubes or inner hull linings? hull contact of separated by nylon/wood/rubber spacers along the way? Also, can i retrofit a boat like the GB Alaskan with keel cooling without changing the world order?

 

It's called Thermal Conductivity.....measured in BTU's at F degrees per square foot.....Aluminum is about 120, steel 20-30, and pure copper 220......IE copper is the best at conducting heat, thus copper pipes can be of the smallest area.

Easy, just get a couple of these http://www.waltergear.com/kc.htm But you still need to pump water to cool the wet exhaust.....which is a shame......

 

I get it(BTU. I misunderstood. I thought when you referenced steel and aluminum, that you were talking about hull materials, not piping. I guess there is no way around the wet exhaust on the Alaskan??

 

There's always a way, just no reasonable way.

Sorry, but I think you are WAY overthinking this. An Alaskan is a fine vessel, better than most and I think would make a fine looper. Take the engineering in the vessel, make sure it's seaworthy and functioning properly, and take off.

Re engineering something like keel cooling or dry stack or a sea chest just because you don't like through hulls is an unfounded concern, Some very good people have been developing the systems on Grand Banks Yachts for decades, they are quite adequate for the great loop. Doing all or any of the above changes on an Alaskan, in my opinion, is ill advised.

$0.02 Steve

 

Whether the cooler is a integral hull tank or piping the heat transmission principal stays the same, and surface area must vary with material and required amount of cooling. Just as cars have different sized radiators.

There are lots of ways "around" particular systems. Question is do any of them make sense? Tearing up an known entity such as stock Alaskan to do something "oddball" is generally a poor investment. Better to spend money on things that are broken or find smart ways to improve the existing stuff. Every system you adopt will have have it's downside as well. IE keel coolers means 4 new holes in the bottom of your boat. And they are vulnerable to damage from debris or ice.

 

You're probably right! Although it appears to be a "long range" boat, i'm not sure the Alaskan is set up to voyage anyway. It would make a nice first boat if we could get in it for the right price. They are supposed to be sending me more info on the one in Kentucky.

 

And Steve, overthinking yes, absolutely. But you have to understand that i have been away from the water in lessor North West for almost 10 years. Sitting and waiting on the hopeful closing on our home/property here so we can get back to the gulf with a reasonable amount to pay cash for a decent used boat. So my day can consist of continuing to work on a property that is under contract as it is, or plan for the first (loop), and second(ocean) boats.