Motor Size

[Rou-Coo]

Originally Posted by denverd0n

Rules of thumb are okay for getting you into the ballpark, but beyond that they don't tell you much.

On the other hand, if you see a motor as a necessary evil, to be used only when there is no alternative, then you can probably get by with a smaller motor.

I have to disagree with the rule of thumb that you give. I only use a motor when necessary (or when my wife tells me to!). So when I do need to use a motor it can be a fairly critical situation - that is when I want a few extra horses. Not the bare minimum for putting into and out of anchorages.

[Weyalan]

As my rule of thumb, the motor (and prop) needs to be big enough to motot off a lee shore in strong wind and a heavy sea. I mention the prop, because it is no good having heaps of power in the engine and an under-spec propellor. Our motor is big enough for the boat, but the current prop is too small - I am currently putting money away to upgrade the prop.

[zeehag]

the size engine depends on the keel type and hull shape and the purpose of the boat. a sloop used mainly for racing and the engine gets it in and out of the harbor--wont neeed much--for a 35ft ericson mII they used a 20 hp engine...but then, that yanmar WILL get you into and out of bad stuff in that boat very easily. my formosa has a perkins 54 hp engine now--it was cruised to here from sf with a 37 hp westerfreke.....the westy actually did a decent job of pushing the boat--but the perkins will do some better---i prefer 54 hp over 37 with a 41 ft deep keel heavy displacement cruiser. i would prefer a bit more, but this will do fine.
the sloop i cruised for a near year in the gulf was a 37 with a 28hp or thereabouts yanmar--did fine in storms and with head winds--coulda been a bit goosier but was adequate...