Diesel Repower

Post by **dougl33** » Mon Jul 02, 2007 6:34 am

quote:Originally posted by JohnD It seems that yanmar boats are turning better cruise #'s than cummins (based on B31 and B33 owners). I'm not so sure I agree with this comment. At least for the 33's, it seems as though the 300-315hp Cummins 6BTA's are turning slightly higher cruise numbers than the 315hp Yanmars. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

Captain Dan McClarren · Mon Jul 02, 2007 8:09 am

Terry, Here are some numbers to look at from my re-power last winter. Bertram 33 Sportfisher Cummins 330B 315 hp ZF 220A 1.75:1 Prop Nibrel 24 x 24 — 1 3/4 four blade Idle RPM 650 Speed 5.2 kts. This speed can be reduced by engaging the trolling valves. RPM 1000 Speed 7.8 kts RPM 1200 Speed 8.9 kts RPM 1400 Speed 9.7 kts RPM 1600 Speed 11.6 kts RPM 1800 Speed 15.1 kts RPM 2000 Speed 18.1 kts RPM 2200 Speed 20.8 kts RPM 2400 Speed 23.4 kts RPM 2600 Speed 26.7 kts WOT RPM 2850 Speed 29.4 kts as per the vessel GPS All numbers above are with boat fully loaded with fuel, equipment and six persons onboard.

Post by **dougl33** » Mon Jul 02, 2007 8:29 am

Cummins docs will state you can cruise at or below 2600rpms. Most dealers/installers will tell you to operate around 2400rpms for maximum engine life. I have 300hp 6BTA M2's (I purchased them as running take-outs). I am swinging 21x22 3 blades with a med cup on 1.53:1 ZF 220A's. My numbers are almost identical. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

BECCA ROSE · Post by **BECCA ROSE** » Mon Jul 02, 2007 1:18 pm

I'm getting the same numbers Dan. 3 blade 21X22. Very happy with what I'm getting. Bill 1988 33 FBC Ipswich, Ma. > ~------- [img]http://www.bertram33.com/photogallery/p ... a_Rose.jpg[/img]

Terry Ray · Post by **Terry Ray** » Thu Jul 05, 2007 7:09 pm

Wow Guys, I've not been paying attention for the last few days,I have been deaply engrossed in the Big Dog, we sea trial in 4 days and I'm behind getting the last connections made. I appreciate all the advice, I have been wondering if anyone has installed engines in the 350-450HP range; I wonder if the stringers and the hull would tolerate the higher horsepower? I have been trying to figure out how to post the pics and have read IR guys thread on how to do it but I'm afraid I'm not that smart. Meanwhile the engine spaces have been scrubbed clean and will have final power washing before Saturday, which will be spent removing hardware from the exterior of the boat. Till Next Time Terry Ray Port Isabel, TX 1981 33'FBC "Little Dog" .

IRGuy · Post by **IRGuy** » Fri Jul 06, 2007 5:11 am

Terry... As of earlier this week the pic posting function for this forum was not working.. that may have been your problem. When it gets fixed someone will post something so we know it is back on line. If, after that, you still can't post them you can email them to me and I will be happy to post them for you. If you don't post often it can be a frustrating experience. Frank B - IRGuy@aol.com "Phoenix" 1983 FBC Wilmington, NC

Post by **dougl33** » Sun Jul 08, 2007 5:23 pm

Terry, In my opninion, anything over 370hp is a waste of money. These boats run best in the 21-26 knot range and 370hp is plenty to acheive those speeds. Shoot, I can run all day long at 23 knots at 2400rpms with my 300hp Cummins. In a pinch, I could run at 2500-2600rpms and get 24-25 knots. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

Brian Davin · Post by **Brian Davin** » Fri Jul 13, 2007 11:04 am

Terry, With the Yanmar 370's I have, the stringers required no modifications. Only one I know of with higher horsepower is Capt Rich out in Montauk with Cat 420's (I think), but be can chime in with his thoughts/experience. Brian '90 Bertram 33' FBC Never Say Never Guilford, CT (Homeport) Kinnelon, NJ (Home)

Terry Ray · Post by **Terry Ray** » Sun Jul 15, 2007 7:53 pm

The Sea Trial is over on the Big Dog, things could not have gone better. Given that we changed the Horsepower,Transmission ratio,the RPM, and the weight of the boat. I figured that we would Sea Trial then tune the props and Sea Trial again, boy was I wrong! We ran the new QSC 8.3-533's through the paces, when we came up to WOT we can to 2660 RPM and showed a load factor of 99% at 28 knots, the cruise at 2400 showed a load of 78% and 24.5 knots. This is a full 5.5 knots over the previous cruise I am happy as a clam in sand, I can't wait to run the load of fuel off to see how fast she cruises with a light fuel load. I guess I can concentrate on the 33' now. I know I still owe you guys Pics. Terry Ray Port Isabel, TX 1981 33'FBC "Little Dog" .