Steve, I’ve been sailing over 67 years. I sail a 1973 Pearson 33. I’m on the verge of installing a Frigoboat Keel Cooler system, which, as you no doubt know, runs the refrigerant tube thru a shoe outside the hull for cooling. However, I have concerns about corrosion and marine fouling, as the shoe cannot be painted. The salesperson that I’m dealing with said (his spelling): "Sailing gurus Nigel Calder, Tom Neal, and Steve Dashew all use and endorse the keel cooler." Tom Neale is not familiar with it and I haven’t yet reached Nigel Calder. Do you have a track record with the keel cooler? Sincerely, from the Jersey Shore, George
Hi George: We are using the keel coolers, but inside the boat in a special aluminum fresh water tank (where the bronze cooler is isolated from the surrounding aluminum). While I have not used these before, they should operate the same as the sintered metal bonding plates which we have used on all our fiberglass designs for many years. You will have to periodically clean the coolers from marine growth, but otherwise it should be fine.
As to electrolytic corrosion, the risks with this should be the same as with any other through-hull. From my perspective, it looks like a very good approach for a fiberglass boat. Regards – Steve
Posted by Steve Dashew (November 30, 1999)
July 2nd, 2013 at 12:56 am
Hi, Steve. I am thinking of replacing the compressor powered fridge and freezer (holding plates) on my 57’aluminum cutter.
I have read that the keel coolers are not recommended for aluminum hulls and here you say that you use fresh water tanks.
Why is that necessary? If the brass cooler is kept well and securely isolated from the hull, is that not enough?
Excuse my ignorance. I always understood that, in order to have an electrolitic current, besides been inmersed in an electrolitic, the metals have to be in electrical contact.
Thanks in advance for your clarification.
Regards,
Carlos
s/v Pionero
July 2nd, 2013 at 6:07 am
Tricky question, the use of dissimilar metals with aluminum. If the heat exchanger is bronze, isolated electrically from the aluminum, and protected with a zinc, it is the same in my mind as a bronze propeller sitting in a rubber cutlass bearing. And we often connect the prop shaft electrically to the hull with a shaft wiper.
July 2nd, 2013 at 1:59 pm
Yes, you are right. That is the case also in my sailboat. But the propeller and the shaft are electrically isolated from the hull and everything else. The zinc is protecting the propeller from the stainless steel shaft.
So, the same should be true of the keel cooler…
I am in no way trying to argue with you. I just want to make this clear to myself because I read so many things that are contradictory or not so obvious.
April 15th, 2015 at 11:13 pm
Hi Steve, I have the same dilemma. An aluminum boat with the top of the keel being a large fresh water tank. I wnat to install the sintered bronze keel cooler into this tank, along with zinc anodic protection. This sounds like what you did albeit in a separate aluminum tank. Has your system worked out satisfactorily?
April 16th, 2015 at 11:15 pm
Hi Pete:
The separate fridge cooling tank has deionized water in it. This has worked fine on a number of our boats.