Bertram33 User Forum

I have a good offer for buy a pair of CAT. Did anyone have or know a Convertible 33 with CAT 3208 375HP. If yes, I can use 1 3/8 shaft? What gear ratio and propeller use? Cruise speed? Thanks for any help. David Vila

The 33's never came with 375hp 3208's. 320hp was the max. I don't think they'll fit the FBC's because the of the gear requirement but I could be wrong. You definately will have to reshaft if they fit, to at least inch and a half but more likely inch and 3/4. On the other hand, I was talking to a member of my yacht club tonight who has a 6.5 (250hp) GM diesel in his 1982 30 foot Sisu. He's got about 1500 hours with no issues. Also, if you haven't been to boatdiesel.com, then I highly suggest you drop the $25 for a full membership. You won't be disappointed. Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA

I am pretty sure they will not fit. These are TA engines and the after cooler will make them too high and since they will require a bigger gear it will be too long. It is a shame, because this would be a sweet package in the 33 FBC. If you do find a way to make them fit the world will be interested!! Ron Callahan SCOUT 1980 Convertible

Just talked to CAT. Said the issue is not the aftercooler since it is no higher than the turbo elbow and goes behind the engine and there is room. I've been throught that. But, the issue is the size of the gears themselves because you will have to get much bigger gears (I have that spec on Twin Disc somewhere) for that power rating and go up to at least a 1 3/4 shaft, maybe a 2. Also, they say you have issues on what they call internal shaft clearance, meaning the lenght of shaft coming inside the boat to connect to the gears to prevent wobble stress. Wobble stress? I've heard that before. I think an old girlfriend said something about that years ago but I am old an cannot remember. Peter L. Banis KNOT AGAIN Boston, MA

Found my Twin Disc specs. Looks like the 5050A gears will carry the load (365 hp at 3300) and if so I know they fit in the space. I was going to do that and had it checked out. But, if you have to go to a bigger gear you have to get it measured. I think the 5050A will take up to 2" (god, I love boat talk!) Peter L. Banis KNOT AGAIN Boston, MA

I think the engines will fit but I agree in the gears issue. I just try to repower my boat without complicated changes because my gas engines work well, I only want to change to diesels for safe reasons. If I buy the Cats 320HP , can use 1 1/2 shaft changing S-Box and the bushings of the struts, using a short gear for fit(correct me if I am wrong).I can buy a used 320HP in USA for 10,000ea without gears plus shipping and tax, I can buy this operating pair for less than the cost of one 320HP and they are here. If the gears for the 375HP not fit I can use one for 320HP and use less cruise rpm and later do the other changes . Any advise is welcome. Peter- Do you know the length of shaft should be inside of the bilge. Thaks David CHISPA P.R.

David, Are you in Puerto Rico? Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA

Yes Doug David Puerto Rico La Isla del Encanto [8D]

David: I don't happen to know how much shaft needs to be inside the boat but I can find out. Will take me a bout a week. I think the bigger the shaft diameter the less shaft inside is needed but I'm surmising. Peter L. Banis KNOT AGAIN Boston, MA

Sorry. Got buried at work. Will ask CAT tomorrow. Peter L. Banis KNOT AGAIN Boston, MA