Claymore's Engine

[claymore]

Is a 1.8 ltr Leyland ( marinised) producing around 48hp apparently.
Sadly it uses around a gallon of water a day through the heat exchanger and has 2 or 3 oil leaks - nothing major but there nevertheless.
A cursory glance at the Beta marine website suggests a smaller unit for the boat.
She is 30 ft overall with a Waterline length of around 26 ft. That is not an accurate measurement.
Claymore is also a motorsailor so my thinking is that being overpowered would be better than underpowered. Flawed thinking or reasonably logical?

 

[Arcady]

so my thinking is that being overpowered would be better than underpowered. Flawed thinking or reasonably logical?

Possibly - but much depends on the actual choice. I agree that for a motorsailer having something a little larger than one might otherwise choose is attractive. However, go too much bigger and you end up with unnecessary weight, an engine that seldom runs at it's most efficient setting, and a more expensive capital outlay.

I recently re-engined our 33' motorsailer (7.5 ton displacement) with a 42hp Vetus and have found that fine so far. Performance wise it matches the old 4.108 it replaced and is about 70kg lighter. I could have fitted something bigger - e.g. the Volvo D2-55 - but decided not to for all the reasons stated above. So far I have found no reason to regret the choice.

Perhaps more important than an increase in power is whether or not you can improve the efficiency of the transmission. Consider a bigger (area) prop and lower reduction ratio for example. My recollection of the Claymore design (Alan Hill?) is that you are probably constrained on diameter in the prop aperture.

The good news is that there is plenty of choice in the power range you require and as already said elsewhere, you can't go far wrong with most modern engines. With the Southampton show coming up soon, perhaps that would be the time to negotiate an end of season bargain???

 

[Deleted member 36384]

Consider a refurbishment of the existing motor, the oil drips and high water consumption might very well reduce. If you're up for doing this yourself, costs can be reduced by you taking the head, block etc to the refurbishers.

 

[Tranona]

A Beta 35 or 38 would be more than enough. The choice would depend on what diameter prop you can swing as the 35 only runs to 2800 so would normally have a bigger prop because of the lower shaft speed. The 38 goes to 3600. Both are normally fitted with a 2:1 reduction.

Speak to Beta for a recommendation - you will need LWL, displacement and maximum prop diameter allowing for a minimum 10% (ideally 15%) of diameter tip clearance.