Bertram33 User Forum

does anyone have a 33 that will cruise easy at 25 knots and have a 30 WOT....how much horsepower do they need honestly and what gear set up...I see a lot on here with 22 or 23 knot cruise with cummins, but to spend that kind of money on a repower, is it going to justify the expense??? Thanks

Bill, I have 300hp Cummins 6BTA's. Gears are ZF220a 1.53:1. I'm swinging 21x22 3 blades with a #5 (aka med) cup. I cruise at 2400rpms. Depending on load and conditions that gets me 23-24 knots. Top end is 27-29 knots, again depending on load and conditions @ 2900rpms. I think you could get a 25+ knot cruise and 30+ knot top-end using Cummins 370B's or similar hp from Yanmar. I know Brian Davin has 370 Yanmars and he can sometimes cruise at 27 knots.

Bill, I have essentially the same setup as Doug but the 330's in a '87 SF. I cruise @24 give or take and it will hit an honest 30 kts top end, a little more without the enclosure. I also still get a little more than 2900 RPM's at WOT so may have a little more if I played with props some more. The difference in handling alone almost makes it worth it but the speed and economy , not to mention the sound of diesels , makes it more than worth it if you can afford it.

Replaced 454's in a 33SF with MarinePower 6.2 LS3's (425HP)cruise at 25kt WOT is 32-33kt. Cruise 0.7gpmile WOT-0.5 gpm. Was ablt to keep orig running gear. Eng/Trans combo ~$20K ea (need new trannys as the LS3 not available in counter ROT)

Thanks for the update. Your's is the 1st gas B33 that cruises at 25kts. I gather you are happy with the results. Al P.S. Did you do the repower or have a shop do it?

Not sure about who was first, but I also cruise (depending on load) at 25 which is about 3500 RPM and top out at 31-32. The diesels certainly take the load much better and obviously better on fuel consumption at the upper end. Fuel injection narrows the gap considerably.

Impressive Joe - please refresh my memory with your power setup. I know you've altered your power curve with the timing, but is that with 454 Gen VI's ? Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA

Rick, correct on the 3 degree timing advance to bring in the max HP at about 4500 which is my max RPM. I tore down new (in 2005)8.1's which were really just bigger 454's with injection. Probably somewhere in the neighborhood of 500HP. I can't believe it's been almost 14 years and almost 2000 hours later, but they still look new.

Sounds sweet Joe, incredible horsepower too. I'm still working with my year 2000 454's Gen VI's....the injection helps a lot relative to fuel burn but my exhaust manifolds are salt water cooled and need to be pulled and cleaned every two years. PITA ! Rick Ticket 85 SF Merc 454 MPI's Falmouth, MA

Bill, I am running my newly installed Vortec 454's at 3100 Cruise (23 knots) and 3/4 fuel. I can cruise at 25 knots at 3300, but I see my fuel use go up much quicker. 3100 seems to be her sweet spot and I am fine w/ 23 knots. I have not bought them up to WOT yet, but can hit 29-30 knots consistently at 3800. Just don't have the stones to bring it up any further, mostly because of the money I have wrapped up in these new engines. The engines are 400 hp, roller Cams, HEI Ignition, w/Predator Carbs (700 cfm) and BW 1.91:1 trannys. Props are now 4-Blade 20" x 20" Dynajets w/cup removed. Generator has been removed and new tank has an additional 28 gals added. I will be concentrating on the fuel consumption numbers this coming season once I get the floscans installed, so more to come. I opted out of the fuel injection to keep the engines a bit more simplistic and because I can always get home w/ a carb. Hope this helps a little. I do have a ton of pics, but always run into issues posting them here. All the best, Jim