We opted for the 330Bs on our 77 36C and are very pleased. If you PM me with a mailing address, I'll send you a copy of the data from the sea trial done by the Cummins engineer/rep. With 1/2 fuel and a light load/clean bottom (travel lift showed about 23,000 lbs, but who knows) the boat did about 29 KNTS @2860 RPM WOT. Props were 22x24 3 blade Michigan Nibrals, 1.5 to 1 ZF trans. Sweet spot for cruise was around 24KNTS @ about 2400 RPM. Now that the boat has gotten fat (25,000 lbs?), tuned props down to 22x23 to reach rated RPM, and have lost about 1 KNT across the spectrum. We went with the 330Bs, because of great reports from local commercial folks on reliability of these mechanical engines, and just not wanting to get the most hopped up version of the 5.9 liter B series. Power and torque for the 330/370Bs are the same from idle to 2800 RPM. The 370B electronics get another 200 RPM WOT, and that's where the addional HP comes from. As you already know, these boats are quite sensitive to weight, and if you want to cruise above 22/23 KNTS, with a heavy boat, you can use the extra HP, but will have to turn higher RPM. In order to compare these boats with these engine options, you have to know weights, trans rations and prop info. My sea trial data is hand written, and not in a form that can be posted. Since we have so many series one 36Cs on the forum, it would be interesting to see if we could post a survey where basic data on these boats (engines, weights, trans, props) was listed along with RPM, speed, GPH and other key performance info. Would really help those considering repowers, and also help the rest of us to get the most out of our great little boats. Maybe one of you who knows the forum better than I do can think of a way we can share this data. Other large hat populations on the forum are always exchanging performance info, but it would all be more useful with a standard format and set of critical boat parameters.
ohiohatteras, if you really like your boat and plan on keeping her a long time you will be thrilled with either 330s or 370s. Good luck, and let me know if you want any info/lessons learned from our recent repower.
Best Regards, Bob K