Rough Guide to Engine Selection for Yachts

Use this table as a rough guide only when selecting the size of engine you require for displacement hulls / sailing yachts. The assumption is that you will wish to reach maximum hull speed and require a suitable engine to achieve this. This assumption may not be correct if you have a racing yacht and only want limited power to reach your moorings; or conversely you do motor sailing with your family and wish a 30 percent safety factor.

You should talk to the hull designer and boat builder for their recommendations of engine power and propeller size (as theoretically they have specified the boats designed performance / hull speed) – the propeller supplier then specifies a suitable propeller to achieve the boats designed performance (based upon engine brake horse power and rpm) - we then supply the required engine.

  • A generally accepted rule of thumb for displacement hulls is 4 bhp per ton for cruising yachts
  • Maximum hull speed in Knots (for displacement hulls) = 1.3 (or 1.4 for a sleek hull) x √ Water Line length (in feet)
  • Beta Marine Limited will not accept any responsibility for incorrect engine selection
Beta 10 10 1 - 2 22 - 24
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Beta 14 13.3 2 – 3.5 24 - 26
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Beta 16 16 3 – 4 25 - 28
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Beta 20 20 4 – 5 26 – 32
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Beta 25 25 5 - 6 27 - 34
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Beta 30 30 6 – 7 32 – 36
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Beta 35 35 8 – 9 36 – 38
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Beta 38 38 9 – 10 37 – 39
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Beta 43 43 10 – 12 38 – 42
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Beta 50 50 12 – 15 42 – 45
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Beta 60 56 15 - 17 43 - 46
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Beta 75 75 17 - 22 46 – 50
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Beta 90 90 22 - 24 50 - 52
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Beta 105 99 24 - 26 51 - 53
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Beta 150 147 25 - 30 52 - 55
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With Catamarans

Ask the Boat Builder / Designer for the recommended engine size. If you have a semi-displacement or planing hull the above guide is not relevant. Please refer to Beta Marine for information.