Or the alternative title to Cast iron keel could be:
Why we love our cast iron keel – A high maintenance affair!
G-whizz, as with all Elan 340s with the deeper 2.1 metre keel is fitted with a composite keel, cast iron foil with a lead (“Elephant’s foot”) bulb. I am not qualified to make assumptions on the benefits of various keel structures, nor do I fully understand the methods used to protect the cast iron in a marine environment. The Broker who sold G-whizz, they were the original Elan agent in Australia, said the reasoning behind the cast iron keel was that it allowed for a finer keel profile, the cynic in me thinks that it allows for a finer profit to the manufacturer. Maybe it is a combination of both.
G-whizz was launched 13 years ago and has performed exceptionally well in those years, requiring only regular maintenance and no repairs due to design issues. However for the past 4 or 5 years the cast iron keel has required a bit more attention than just a pressure wash, sand and repaint during the annual bottom service.
The following photos compare the condition of the keel following a pressure wash just after coming out of the water, the deterioration in 2 years is noticeable.
For the past few year the shipwrights have patched the keel using processes that are a bit beyond my comprehension, however the the cast iron keel continued to deteriorate between the annual services. I must say that the treatments were never promised to be a long term fix, only something to try and get through to the next service – in this regard the were somewhat successful. This year we bit the bullet to do something a little more permanent, we got two quotes from two different yards. These yards suggested different methods:
One; to soda blast the keel and epoxy.
Two; to wire grind then chemically treat the keel.
Quote two was half the price of one. and is the treatment we went for. I guess the success of this decision will be measured when G-whizz comes out of the water next year, although reports from the diver who cleans her on a regular basis will be most anticipated.
Motoring on the way to the shipyard for this bottom service G-whizz was struggling to get to get over 6 knots though the water under motor at 2000 rpm, on the way back to the mooring she was exceeding 7 knots at the same rpm, I wish I took more notice of wind condition on the first journey, but on the return run the was a gentle 3 to 5 knot wind just off the the bow, quite an improvement.
As mentioned earlier we were told that the Cast iron allowed for a fine keel profile, maybe the photo to the right illustrates that.
We are looking forward to our next race, that for a number of reasons is not coming fast enough, just to check G-whizz’s performance against her traditional competitors.
For those with a better technical mind in these matters than mine, the base treatment of the corrosion on the cast iron keel was Feronite, which I believe to be manufactured (or distributed in Australia) be Boatcraft.
I guess this whole process give us an insight into the trials and tribulations of those that have steel boats.