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bertram 42 v 37 v46 which is best

Discussion in 'Bertram Yacht' started by todd, Jul 29, 2011.

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  1. todd

    todd Member

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    Hi,ive been looking around for a while and it seems like eveyones got differing thoughts I`d love to hear form any one whos had a 37, a 42 or a 46, fuel burn is an issue ,as are engine repowers,as alot of these boats are up for new engines,one boat I`am looknig at is a42 with 6-92s but they need replacing,anyone done a repower on a42? how did you get the motors out and in,any and all thoughts would be appreciated
    Todd
  2. AdrenalinJunki

    AdrenalinJunki New Member

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    I've had the port engine out of my 42' once. A VT903 will come out a center door with the exh manifolds off. The 42' is lighter than the 46', so a little better on fuel. They're both great boats. There's a 46' in this area with the 660hp QSM11's that flies. I will be repowering my 42' in a year or two. My mechanic wants me to go with B series Cummins, but I'm also lokking at the QSM11's. Good luck in your search, there are some great deals out there right now on boats that are due for total re-fits.
  3. Manny

    Manny Senior Member

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    When I was in the market for my first boat, I was between a 37' with CATs and a 42' with 6-92's. I sea trialed both and both were amazing boats, but my preference went to the 42' because it was faster. However the owner backed out from the sale so I ended up buying the 37'. I have absolutely nothing negative to say about it because it was a simply amazing and reliable boat. sure, speed wasn't outstanding but the ride was spectacular. I think up to this day the 37' had a dryer ride than my current 54', and I think the ride is almost as good as the 54'. Personally I prefer detroits over any other engine because they're reliable, they're the cheapest to maintain, and parts are easy to find... although the CAT's my 37' had never gave me any issues so I can't complain. Afterward I thought of moving up to a 46', but as it turned out the boat's ride, I thought, wasn't as good as the 37' or 42', so I backed off from getting one...
  4. AdrenalinJunki

    AdrenalinJunki New Member

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    I've also fished on a 37' that had been repowered with 440hp Yanmars, instead of the original Cat 3208's. Nice boat, and very economical with the new Yanmars.
  5. jhall767

    jhall767 Senior Member

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    What hp engine would you be replacing with the B-series? And what hp B-series. 480? I keep looking at them to replace my 450 hp 671 TI's but I'm just not sure there is enough beef there without overloading the engines. On paper yes. In the real world I don't know. Also what about a QSC at 600?
  6. Capt J

    Capt J Senior Member

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    I've run several sets of the B series, mostly in 35' Carolina Classics and they're a good running engine. Torque monsters they are not. In all of the boat's I've run with them, they seem to lose 100hp each SOMEWHERE after 200 hours as every boat I've run with them would not achieve top rpm by about 200 rpm's. One had a set of the 450hp, the other had a set of 480hp, and I've also run them in searays and such. The 35' Carolina Classic with the 450hp already had 1200hrs on them, I ran it from Pensacola, FL, to Falmouth, Mass over 13 days and they never missed a beat and might've used a quart of oil each, total.

    Personally I think 3126's would be a better fit. The QSC's would be my choice (providing they fit) as they do have a lot of torque to get a heavy boat on plane, and the more hp gives you a better cruise and you can always run them slower and conserve fuel if need be.
  7. AdrenalinJunki

    AdrenalinJunki New Member

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    I thought they had a B series at 450hp, but that might be the 480hp now. I have heard of one, possibly two 42's being repowered with the QSM11's. I'd love to talk to someone with some first-hand experience, and see some performance numbers from one of those. I'm looking at the 660 hp version. I'm going to the FLIBS next week, and plan to stop by Cummins, Cat, and Yanmar.
  8. RER

    RER Senior Member

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    Which Cummins B series has the HP you all are referring to in these posts?

    Do you mean Cummins 6C or 450C ...?
  9. jhall767

    jhall767 Senior Member

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    The 6C or 450C is the older mechanical style.

    QSB (5.9L) is available in 480hp in a recreational rating

    QSC (8.3L) is currently available up to 600 hp I believe.

    QSM11 (10.8L) is available up to 715 hp.

    I was curious about his mechanic proposing a 5.9L engine in a heavy 46' boat where people are saying a 692 550 hp engine is not enough. Now I understand that maybe some of those detroits may have had the hp numbers embellished a bit but still...
  10. Capt J

    Capt J Senior Member

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    or embellished a lot in some cases! The 92 series also seemed to lose the majical 100-200hp after 200 hours of usage also. I know of a lot of boats with 12v92's, 8v92's, 6v92's that had to lose 2-3" of pitch off of the propellors because at a few years old, they were miracuously overloaded and couldn't achieve top rpms...... 71's never seemed to have that problem.
  11. SHAZAM

    SHAZAM Senior Member

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    42 and 46 are the old style bottoms designed to do double duty as platforms for both sf's and motor yachts, while the bottoms were decent there was plenty of room for improvement. The 37 is a scaled down version of the 54 as was the 43 and the 50, fantastic running wide chined deep v's.

    As far as repowering with B series cummins, those engines do not have the off boost torque low down to be adequate for even a 37. I had a 30 moppie with 6bta 370's and believe me it was a pig till the turbos spooled up and had a hell of a time getting on plane.

    I've put together several convertibles based on the 37 hull with qsb cummins (540's and 600's) with acceptable results (35 knots) but that hull really came alive when powered with m-11's, 38 knots with 535's and 41 knots with 660's (a little scary). With the m-11's and 1.76:1 gears, the boat would get on plane from a dead stop in just under 4 seconds.
  12. AdrenalinJunki

    AdrenalinJunki New Member

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    You're putting QSM11's in a 37' hull? Jeeeeze! My mechanic was talking about the QSB, and mine is a 42', so it's not quite as heavy as a 46'. My current power is VTA903's @450hp, and it gets decent performance. Surprisingly she gets out of the hole easily, and I'm making 20kts@2000. At WOT 2600rpms makes 26kts, and that's with a full tower. Those 903's weigh in at 3600lbs, and the QSB is 2000lbs, IIRC. I though if I had even the same HPand I dropped 3200lbs it would up that cruise to 24kt range. Where I may not get that is TQ. Those 903's do make some strong numbers in the TQ department, which seems kind of dependent on cubic inches.
  13. jhall767

    jhall767 Senior Member

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    Yeah that's the question. Does 480 (metric) hp at 3400 rpm in a light engine equate to 450hp in an engine twice it's weight. These engines have very flat torque curves due to the computer controlled injection. The additional gear reduction for 3400 rpm from a 2500 rpm engine will multiply that torque further. The QSB 480 peak torque is 942 ft/lbs x 1.36 works out to 1280 ft/lbs. The numbers say yes. The gut feeling not so much.

    BTW I think the QSB weight is closer to 1400 lbs. Maybe 1650 lbs with a trans.
  14. SHAZAM

    SHAZAM Senior Member

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    My cummins rep promised me equal if not better performance if I switched from 535 M-11's with 1.76:1 gears to 540 QSC's with 2:1 gears. Although on paper it should have been the same if not a little better because of the QSC's lighter weight, in reality it wasn't even close. That's why I wouldn't even consider the B in such a big boat regardless of the HP.
  15. Trinimax

    Trinimax Senior Member

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    There is a 42 bertram here in trinidad that had 903 cummins and was powered with 540 hp cummins diesels, not sure what model, but speaking to the owner he said his boat cruises at an easy 24 knots without pushing it, and tops out at a lil over 30 knots. Also another benefit of the lighter engines is that the owner was able to add an extra 200 gallons of fuel under the cockpit as the boat floated bow down with the lighter engines.

    hope this helps

    GMax
  16. AdrenalinJunki

    AdrenalinJunki New Member

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    And that's why it'll probably be QSM11's. Because irregardless of the outcome, I'm stuck with it.