Bertram33 User Forum

Great numbers Dan, and pretty much what all the 300-315hp 6BTA guys are getting. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

Thanks for all your input. I am going to start to look for props most likley 21x20 4 blades. I need to get my boat up to the numbers all of you are getting Michael 33SF

Any update on performance?

I am still on the fence as to what to do.I have spoken to Tuckerton prop,Atlantic prop and Michigan wheel. Everyone had the same answer"Well maybe you will get the numbers you are lookin for"I pulled the boat yesterday for the winter so that will give me some time to think about it Michael 33sf

Michael, Can you please refresh us as to what your final numbers were at the end of the season. With the 370B's (355hp) you should prop them to hit 3100rpms at WOT. Also, per Tony Athens at boatdiesel, the no load WOT on the 370B's should be 3400rpms. Did you ever verify that you were getting to that? No offense, but your boat seems way to slow for the power you've got. With your gear set up, I would think a 3 blade 21x22 prop with a light cup would make the boat scream. At 21x19, I don't think you could change the pitch enough on your current props to help you out (I've been told 2 inches is the max change). You could probably go to a 21 inch pitch and add a heavy cup. Finally, while the boat will run more smoothly with a 4 blade prop, if everything else is equal the boat will be slower than with a 3 blade. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

Doug No offence taken.I am just looking for a real answer. Everyone I have spoken to are all non commital. I spoke to a Cummins rep on Friday.He said that yes my boat seems slow.(THANKS ALOT). He did say that in neutral the engines should rev up 300rpms over the top,which in my case should be 3300rpm's.I have never checked and now my boat is out of the water.I asked Carey's Diesel who did the repower if the engines were photo tached and they said yes(I AM BEGINNING TO WONDER). Under load my stbd engine tops out at 3050rpms and the port at 2950 rpms which is where they are supposed to be.At 25-2600 rpms on a calm day with no tide I am running between 19-21 knots.Wide open I will do 25 knots.If we were talking about picking up 1 or 2 knots I wouldn't even be considering a prop change but 4-5knots is a big difference.I get the same speed whether loaded to the gills making an offshore trip or unloaded with a 1/2 tank of fuel just cruising around,which is the nice thing about diesels. One thing that I do have different than the rest of you is that in the stern where the generator is supposed to be I have a second fuel tank which holds 108 gallons. I put the generator forward under the salon floor right on the other side of the engine room bulkhead.My water tank(28GALLONS)is forward of that.I also have 1 3/4" shafts where I see most of you have 1 1/2".The boat does not seem bow or stern heavy and runs straight with no pitch and no need to use the trim tabs. The Cummins rep did say that Michigan has come out with a new wheel model DXL??? which is supposed to give you better performace when using the same size wheel. I am considering purchasing a set of 21x22 or 22x22 props.I have plenty of room to put a 22"prop.My only concern is overloading the engines plus the trial and error expence.Another concern is what happens on the low end.I do alot of trolling for striped bass in the spring.At idle my boat does 4 1/2 knots+- which I find borderline for that type of fishing. What manufacturer of props are all of you using and are the bronze or nibral. The more I talk to different people the more confused I get. Thanks Michael 33sf.

Michael... I am late into this discussion, having stayed out because others here are more knowledgeable than I am, but perhaps a fresh view would be helpful. My 83 FBC with Cummins 6Bs (1998 315/330 HP), (lightly loaded) and a 1.5:1 trans ratio hits about 24-25 knots at 2,500 RPM.. never ran at WOT for very long (only during the sea trial actually) but they hit 2950 RPMs at that time... and I have 21"D x 23" P 3 blade no cup props. According to Tony Athens and other diesel guys I trust I am right where I should be with my combination of factors. My engine/prop/trans ratio/speed numbers seem typical of several others here.. ie: Buzz Kistler's "Buzz Off", Bill Dunlap's "Becca Rose", and Doug's "Queen Elizabeth". All pretty much the same boat, engine prop combinations, although Buzz's trans ratio is higher than mine (I believe he has 2.0:1, but he also has larger diameter props). We all seem to have pretty much the same performance. It seems you are either underpropped or have a higher transmission ratio than you think, from what I have read here. You can measure your RPMs (although if your techs are to be trusted they have already been photo tached), and you know your engine HP. That leaves your props and transmission ratios in question. Since you are on the hard you can easily check your prop characteristics, but are you completely sure of your trans ratio? You might not be turning your props as fast as you think if you are only reading your engine RPMs. This might be a lame comment, but when the data all seems right but the performance is not typical, I would start over and verify everything.. starting with the easiest things to measure. Frank B - IRGuy@aol.com "Phoenix" 1983 FBC Wilmington, NC

Frank, I think Buzz has 1.75:1 ratios on his trans. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

I have 1.75:1 transmissions on my boat and if I remember correctly my wheels are 23D x 25P three blade Nibral. Buzz buzzk 1988 Bertram 33 FBC Buzz Off Morehead City, NC

i run 35b with 370bs 26kts @2600 rpms @22gal an hour wide open@3050 she runs33kts. i also have 21x22 3 blade mich djx's

I think the 21x20 props will be to small. I would go to atleast 21x22 1/2

I have a 33 Bertram Sportfish W/ B370 Cummins. Cruise is whatever you want from 21 to 28 kts. WOT is 30.5 kts W/ 315 gals of fuel and 80 gals of water. Fuel cons at 26 kts is 19.5 gals /hr. Props are 4 blade michigan. I know most all of you won't believe these #s but they are true......She is a sleeper

Hey Boardfeet, Welcome aboard. What's the slowest you go with both of those 370's in gear, throttle's all the way down ? In other words, how slow does she troll ? Rick Ticket 85 SF Falmouth, MA

Frank, Welcome aboard. What year is your boat. How about trans ratio and prop size. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

Some good info from Boatdiesel.com's Tony Athens. Yes, you can think of the 370 as an up-rated 330 or visa versa. The life of either engine is more dependent upon your throttle hand and whether the engine has been propped right and maintained well since day 1.. If things are right, seeing a few 1000 hours out them in recreational service is easy.. Seeing 10,000+ hours is commercial service where the engines spend much time below 2000 RPM is also very easy. Overpropped and run by an owner who is ignorant of the proper operation and does not know the limitations of the engine, then engine life can be very short. The 330 needs to see an accurate 2900+ RPM at WOT with the vessel fully loaded.. The 370 needs 3100+ under the same conditions. If these WOT RPM,s can be reached, and the boat performs well at 300-400 RPM below rated, you are in great shape. If your vessel is very heavy and either engine needs to be run at about 200 below the rated WOT to maintain the speed you want, I would consider the vessel under powered and engine life will be limited........... And last, these are very good engines in either rating, are easy and cheap to maintain, and if you read and follow the advice on these forums as to proper operation, you'll become a happy owner for years to come. Bill 1988 33 FBC Ipswich, Ma. > ~------- [img]http://www.bertram33.com/photogallery/p ... a_Rose.jpg[/img]