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I am considering replacing my Volvo Penta MD30 Engine on my Seaforth. I would be grateful for advice on what is the appropriate HP for a new engine, or the best way to work out what might be appropriate. Thank you
I have a Beta 10 on my Mac 26 and have been very pleased with it. It’s quiet and very economical. Of course, you’d need a larger engine than mine but Beta offer a range of diesel engines from 10 to 98 HP and I’m sure they would advise you re size. I’ve always found them very helpful. They advertise every month in Practical Boat Owner but, in case you haven’t got a copy, their website is http://www.betamarine.co.uk.
Thanks Geoffrey. I have talked with Beta who as you say are very helpful. They have advised 30 or 35hp. However, I recollect another Seaforth owner saying they have a Beta 50 which they were very pleased with, and my current Volvo Penta is 65hp. I just wonder if there is some formula based on weight and shape? Thanks again.
Hi , I would go for the larger BHP as the Seaforth is a big heavy boat. We have a ford Melody 88HP and its very fuel efficient. more horsepower les RPM makes for a quieter and more fuel efficient sail. We manage 6kts at 1100rpm with a fuel burn of about 3ltrs an hour
Hi Charles
Bit late with this reply so hope its still relevant
I have a 50hp Beta which I am really pleased with. It replaced a mercedes 42hp which was knackered. I was also advised by Beta that I probably didn’t need 50hp but since I knew that some had been fitted with volvo 65hp I thought it would be more than adequate. Spares are easy and not too expensive. I can get 6 -7 knots .
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No doubt your decision has been taken, but if any others are thinking about a new engine, I have a some comments : my first MW27 had a Volvo MD2B, which was certainly the right power (23hp at full speed), to punch against the strongest foul tide or headwinds, but it was so heavy that the stern of the boat was pushed down, creating extra drag, and sailing performance was permanently affected. Under full engine power as well, I could create impressive waves coming up the river if I wanted to get that last half a knot !
My current MW27 has a 3 cylinder Beta 20, which is best part of 100kg less cast iron than the Volvo, so the hull is sitting much better on the water, and the effective top speed is almost identical.
in between the 2 Macwesters, for 5 years, I owned a lovely Moody 37 (around 8 tons, and 3.8 metres beam) , which had the same BMC 1.5 litre 4 cyl diesel as most Malin and Seaforth. The difference was that it had a 3:1 ratio gearbox and a massive 3 blade prop. That means a lot more effective « push » for berthing manoeuvres, and in the worst of conditions, like one day in a thundery line squall with over 40kts of headwinds. The photo was taken a few minutes before, whilst we were lifting the anchor to get clear of the shore.
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