HP Upgrade, Shaft & Prop Sizes

Sean B · Post by **Sean B** » Fri Nov 12, 2004 4:27 am

I have a 33B SF that has 260 HP 3208T Cats, 1.375" Aquamet 22 shafts, Model MG502-1 twin-disk 1.54:1 trannys, and 3-blade 20x22 props. All this is stock on my 1987 model. I've found that to cruise at optimum 20-21 knots I have to keep the motors at ~2600 RPM, which is a little higher than they should run at. I've researched and learned than I can boost the engine output to 320 HP by changing some things about the injection pump and governor. My question is to those who have this boat and 320 HP engines: what size shaft and prop do you have? I know that my shafts are marginal and I intend to upgrade in the future, but want to do engine upgrade now and keep existing shafts for the time being. If anybody has stock Bertram 33 with 320 HP I'd be really appreciative to know what size shaft, prop and tranny ratio the boat came with. Thanks!

Post by **dougl33** » Fri Nov 12, 2004 5:39 am

Sean, I'm really surprised that you only have inch and 3/8's shafts on your 87. Thats what I have on my 86 with gas. All of the 87's (all with gas) that I've seen have had inch and half shafts. I always assumed that Bertram shifted over to inch and half for everything sometime in late 1986. Weird. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth

Sean B · Post by **Sean B** » Fri Nov 12, 2004 10:20 am

That's interesting. A couple of people I've talked with that actually worked there said 1.375" on both gas + diesel setups was common. Maybe they did different things at different times, I don't know. Sometimes people will say that the Aquamet 22 is so strong or so elastic that you don't need bigger, but I know previous owner changed them a couple of years ago, and I doubt it was for fun... It is disappointing that they put such a small shaft on an otherwise good boat. Wish they would have gone to 1.75", which is where I'm heading. Hopefully someone here has similiar 320 HP setup and can tell me about their shafts, trannys, and props

franklyprice · Post by **franklyprice** » Fri Nov 12, 2004 2:07 pm

Sean, For what it`s worth, the spec. sheet that came with my boat (`87)with the owners manual states that the gas engines used a 1.5" shaft and the diesels (270hp cat 3208)used a 1.375" shaft. I assumed this was a mis-print or someone just got it backwards . I also thought but am not sure that earlier than `86 it was just the opposite. It`s baffling why they would put a smaller shaft with the diesels on these later boats. By the way, how do you like your boat? Is the diesel smokey? Do they vibrate the boat a lot? How do you like the 3208 in general? I`ve been tempted to get a couple rebuilt 375 hp cats because they`re so bulletproof but am scared about smoke and noise/ vibration. Frank Price `87 SF "JEANNE CLAIRE" Rowley Ma

Sean B · Post by **Sean B** » Thu Nov 18, 2004 8:12 am

I like them just fine. They smoke some, like all diesels, but it's not excessive. No bothersome noise or vibration. quote:Originally posted by franklyprice Sean, For what it`s worth, the spec. sheet that came with my boat (`87)with the owners manual states that the gas engines used a 1.5" shaft and the diesels (270hp cat 3208)used a 1.375" shaft. I assumed this was a mis-print or someone just got it backwards . I also thought but am not sure that earlier than `86 it was just the opposite. It`s baffling why they would put a smaller shaft with the diesels on these later boats. By the way, how do you like your boat? Is the diesel smokey? Do they vibrate the boat a lot? How do you like the 3208 in general? I`ve been tempted to get a couple rebuilt 375 hp cats because they`re so bulletproof but am scared about smoke and noise/ vibration. Frank Price `87 SF "JEANNE CLAIRE" Rowley Ma

Rick · Post by **Rick** » Tue Nov 23, 2004 11:39 am

I have a 1985 33SF w/ 1 3/8" shafts and one of them snapped ! Snapped just aft of the Starboard strut while cruising at 3,000 w/ my gas Merc 454's. When I called Bertram to get a shaft length measurement, he said "let's see....an '85 33SF.....you have 1.5" shafts....". I called time out and explained to him that they were indeed 1 3/8" and upon further review he came back and told me that there had been an upgrade years ago to re-fit all 33's w/ 1.5" shafts because they were snapping. I didn't even ask how much parts were, knowing I was easily looking at $7,500 to start. I've had the boat since 1997 and that was the first to go. So I'm not sure what to expect for frequency, but that job will have to wait until it's time to repower...again. Could be that the shaft had minor vibrations which exacerbated the situation, who knows. I was loaded up with people and a full tank of gas which I'm sure didn't help but I was no where near the full throttle of 4,400 either. They're heavy boats. Most boats with much less of our weight use a 1 3/8" shaft, it all made sense when put it all together. The 1.5" shafts are on my list but will probably stay there for a while. Fair winds, following sea's, Rick

Sean B · Post by **Sean B** » Tue Nov 30, 2004 11:52 pm

I wonder when Bertram did the "upgrade" because they were still using 1 3/8" in 1987. Did they do it for free? Not that it matters much now, but I'm curious to see how bad they perceived the problem to be. How did you get to your $7,500 estimate? I think that if I do it I'll go up to the 1 3/4" shafts, and the new heavier Bertram struts that are available at HighTide Marine (got to change the struts anyway, I'm told). Anybody know how hard it is to change out struts? I think they're under the fuel tank. Is this something I can do with my Craftsman tool kit (ha ha) quote:Originally posted by Rick I have a 1985 33SF w/ 1 3/8" shafts and one of them snapped ! Snapped just aft of the Starboard strut while cruising at 3,000 w/ my gas Merc 454's. When I called Bertram to get a shaft length measurement, he said "let's see....an '85 33SF.....you have 1.5" shafts....". I called time out and explained to him that they were indeed 1 3/8" and upon further review he came back and told me that there had been an upgrade years ago to re-fit all 33's w/ 1.5" shafts because they were snapping. I didn't even ask how much parts were, knowing I was easily looking at $7,500 to start. I've had the boat since 1997 and that was the first to go. So I'm not sure what to expect for frequency, but that job will have to wait until it's time to repower...again. Could be that the shaft had minor vibrations which exacerbated the situation, who knows. I was loaded up with people and a full tank of gas which I'm sure didn't help but I was no where near the full throttle of 4,400 either. They're heavy boats. Most boats with much less of our weight use a 1 3/8" shaft, it all made sense when put it all together. The 1.5" shafts are on my list but will probably stay there for a while. Fair winds, following sea's, Rick

CB35 · Post by **CB35** » Wed Dec 01, 2004 2:28 am

You may be able to put 1.5 inch cutlass bearing in your existing struts!! Bertram usually used thick wall cutlass bearing; so if you go to a thin wall bearing you can probably go to 1.5 inch shafts. I have a 35B with 300HP 3208Cats. My boat has two struts per shaft at 1.5 inches. The trannies are 1.5:1TD's 506's I think. Props are 20X22 cupped for a 2850 rpm at full load. By the way my Cat diesel mechanic said it was waste of money for me to go to 320HP. He said you really don't get anymore torque than what I have at 300HP. Maybe 260 to 320HP will make a difference. Charlie

Post by **dougl33** » Wed Dec 01, 2004 3:24 am

The struts are not beneath the fuel tank. I know this because everytime I need to get into the bilges next to the gennie I always wind up stepping on the bolts that hold the struts in place. Ouch! Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth

Sean B · Post by **Sean B** » Wed Dec 01, 2004 5:34 am

Looking for 1.75" shafts, so I need new struts quote:Originally posted by CB35 You may be able to put 1.5 inch cutlass bearing in your existing struts!! Bertram usually used thick wall cutlass bearing; so if you go to a thin wall bearing you can probably go to 1.5 inch shafts. I have a 35B with 300HP 3208Cats. My boat has two struts per shaft at 1.5 inches. The trannies are 1.5:1TD's 506's I think. Props are 20X22 cupped for a 2850 rpm at full load. By the way my Cat diesel mechanic said it was waste of money for me to go to 320HP. He said you really don't get anymore torque than what I have at 300HP. Maybe 260 to 320HP will make a difference. Charlie

Sean B · Post by **Sean B** » Wed Dec 01, 2004 5:35 am

Now that is the first good news I've heard since I started researching this thing - Thanks! Guess I'll get my socket set out soon quote:Originally posted by dougl33 The struts are not beneath the fuel tank. I know this because everytime I need to get into the bilges next to the gennie I always wind up stepping on the bolts that hold the struts in place. Ouch! Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth

lobsta1 · Post by **lobsta1** » Wed Dec 01, 2004 6:08 am

Sean, as Charlie stated, there is a very good chance that the struts are bedded in glass putty mixture. That's what I found out two yrs ago when I had to pull out the complete rudder ports due to leaking. Bertram used the putty to line things up against the curvature of the hull. On my ports that mixture was cracked allowing in the water. I would guess the struts are done the same way. If that's cracked,(or gets cracked when removing the struts) you will have to redo with an epoxy putty & get everything lined up again. Good Luck Al 1978 33 FBC NITES OFF

mak6190 · Post by **mak6190** » Mon Feb 14, 2005 4:26 pm

Sean, I have a 1982 33SF with the 275HP Cat 3208s. Props are brass 21X21 with MG502s. The shafts are 1 3/8 and they have done well for the last 600 hours or so. I also have the original papers with all the information pertaining to the as built specs. Fuel as shipped was at 315 gals. The exhaust system is the type that comes out the sides in a rectangular shapped vent and the cooling water comes out of two smaller tail pipes at the stern that are about 2" in diameter. Boat is very heavy. I had the props set at 21X 22 which gave me a 18.2kts. cruise at 2350 RPM, but the engines would not turn over 2600 to 2700 rpm. I had them set back to 21x21 and they are now runnnig 18.5 kts at 2450 -2500 rpm. The engine now even pass the 2800 RPM upper end. I would like to say that the motors have around 3500 - 4000 hours of use and I have put over 600 hours since Feb 2002. Engines do not smoke. They are much cleaner buring than most diesls I know of. They also run very smooth. Fumes do bother a little while you are in idle or trolling with a slight wind in favor. I left the props with this pitch to keep it a little easier on the engines. I have heard of a boat similar to mine but with Yanmar 420Hps cruising @ 30kts. Hope this information helps. Mike Pto. La Cruz Venezuela

sbeer · Post by **sbeer** » Fri Feb 25, 2005 8:45 am

Mike, I have the 81 sf with direct exhaust out the back. 3208 320hp. I wonder if all the early 80 33's had their exhausts set up like that? I never noticed! I guess that truely dictates that mine was a conversion. Mike

Sean B · Post by **Sean B** » Wed Mar 16, 2005 8:01 am

I think that any diesel-powered B33 with the 315 gallon tank was a gas-powered boat when it left the factory. As a rule, they used the 250 gal tank in diesels and the 315 in gas. (correct me if I'm wrong). It's not hard to imagine that maybe some custom boats were ordered with diesel setups and the larger tank though. I would love to have that extra 65 gallons of fuel