Stephen
We had some seepage early on, but have cured it with a combination of tightening the jubilees (if you over tighten you oval the pipe as you have found), and not letting water sit in the pipe. We always fill a kettle then disconnect the water (we have the front tanks) and shut off the sea cocks before we sail to prevent the syphoning Paul has mentioned.
Unless they've changed the pumps, don't really understand why you should have a problem, we have the Whale vertical action sink pumps (hull # 29).
Can only suggest you change the pipe for a smaller size. When I was younger than I am now there wasn't this fancy blue BS??? water pipe, my dad used transparent polythene tubing and stuck it in hot water before pushing it over the pipe end, perhaps with the help of a bit of soap (backed up by the jubilee clip of course).
If you have distorted the pipe you might need to change it anyway
The only other thought I have is that white 'silk' thread tape they sell for sealing joints on domestic taps and radiators, but not sure if it would work.
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