I'm looking at options to re-power my Catalina 380 sailboat, and am interested in the Beta 38 as an option to replace the failed Westerbeke 42. Questions I have include: Will the Beta 38 be enough, or should I be looking at the Beta 43 (if it will fit). Can my existing HBW150A (2.5:1) transmission be used, or will I need to purchase a new transmission? Will I need a new prop, or can I continue using my 18 inch H5 Autoprop with a proper transmission?
The 38 should be more than adequate for the C 380 and it is possible to re-use your old transmission but you may find that it will not last long with a fresh engine in front of it. I would either have your transmission freshened up with new clutch plates and thrust washers or get your new engine with a new transmission. We normally fit the TMC60A which is available with the following ratios; 2:1 or 2.45:1.
I have run some propeller calculations for you using a standard three blade propeller with 50% BAR as a guide.
I am not sure about the Autoprop as it is a strange beast. Here I suggest that you contact the suppliers of the Autoprop (Geoff at AB Marine) and ask him to run his special prop calculator for the Autoprop to see you can stay with the prop that you have or if changes must be made.
Thanks for the quick response. I concur with comments about the transmission, and will most likely go with a new one. The original prop on my boat was a fixed 18" x 10" three blade RH, which seems close to your 17.5' x 11" calculation. I recall getting good performance with that prop years ago, but changed to the Autoprop for improvement under sail and motoring. As suggested, I will check with Autoprop for usability on a new installation. The boat information you used is mostly correct, except that I have a wing keel with 5.5 foot draft, and the actual cruising weight is probably closer to 22,000 lbs with full tanks and gear. Don't know if those minor differences would change anything?
The extra weight will have an effect on the vessel's acceleration under power and possibly a slightly lower max speed under power. The propeller however will remain the same.
-- Edited by Stanley on Tuesday 5th of January 2016 08:12:11 AM