Hydraulic keel conversion

last_tuesday · Post by **last_tuesday** » Wed Sep 03, 2008 7:15 pm

Having read through all the forum postings and the newsletters, it would seem that, if the Swift 18 has an Achilles heel, it is surely the keel ( would that make it an Achilles Keel then ?

)

The boat we are getting had the keel mechanism replaced in 2000. At that point it was 10 years old.

The mechanism itself seems to be reasonably easily adapted to hydraulic operation. A ram , hose and pump would cost in the region of £150, plus the time for fabricating brackets etc.... A well thought out hydraulic system is mechanically simpler, less to wear out, should be reliable

A worthy project, or a waste of time? Anyone tried it before?

David

CHERRY PIE · Post by **CHERRY PIE** » Thu Sep 04, 2008 11:53 am

Hi David, I have also thought about hydraulics and lifting keels when dealing with the problems we have endured with the present system, I talked a little with mike from sunny norfolk and was considering some other alternative of raising and lowering the keel. My opinion now after going through trials with differrent screw thicknesses is that the mechanism benefits greatly from "beefing up the mechanism" as I mentioned in previous posts I have tried the slim thrust bearing (broke) and have now arrived at the point where our thicker screw and re-engineered bush do the job perfectly well so long as we use a really good quality waterproof grease.....you have to admit the original design is brilliant! and does not impose the cabin area to much, but it does have a great deal to cope with. I think the keel would benefit from some kind of device to hold the keel in the upright position in order to take the strain of the mechanism when the keel was not in use. Gary

Terry · Post by **Terry** » Thu Sep 04, 2008 2:06 pm

I suspect a lot of problems to winding mechanisms are caused by drying moorings, where, as the tide begins to refloat the boat there is a lot of lifting and lowering. This concentrates strain always on the same point on the thread. This, coupled with the lack of grease late in the season, probably gives rise to most of the problems.
On the face of it, there are lots of advantages with a hydraulic lifting system; besides the fact that hydraulics are generally easier to use, you could have the pump in the cockpit remote from the keel box. Lowering the keel would be a doddle just involving the release of a valve.
The problem with hydraulic pumps is that they don’t cope well with being under constant load, as is when the boat is kept on a drying mooring. You would definitely need some sort of mechanical lock to take the strain off the system when the keel is up. If someone comes up with a working modification I would be interested but in the mean time, Gary’s “beefing up” modification, looks the best option to me. Some invention that would allow for the proper introduction of grease to the thread whilst the boat is afloat would be useful.
PS don’t some Deltas have hydraulic lifting gear?

giraffe · Post by **giraffe** » Thu Sep 04, 2008 3:59 pm

It's an interesting idea. How would the ram lie? I have a feeling that hydraulic rams probably work best when they're pushing (their usual job) rather than pulling.

Terry - do you mean like a grease nipple on the top half of the inspection hatch and a short length of metal tubing inside to guide the grease from your gun to the screw.