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37 Bertram 6v92 550HP shaft size

Discussion in 'Bertram Yacht' started by Breckster, Aug 17, 2018.

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  1. Capt Ralph

    Capt Ralph Senior Member

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    I have re-powered gas 33 & 34s to Cummings.
    You should have the room for a pair of 8V71s (screamers).
    The reman Cummings 8.3s would be a real but kicker for the long run.
    IMO, DO NOT invest into a used pair of 92s.
  2. Breckster

    Breckster Member

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    ^^^^that is AWESOME! Interesting comparison in the torque rise from the 2-stroke v-configuration to the 4-stroke I-6 configuration.
  3. Capt J

    Capt J Senior Member

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    I would NOT repower with 6v92's. There are ways now to get more HP out of the 71;s and I'd long go that route before sticking 6v92's in there...….. But really the ONLY options I'd consider are rebuilding yours in place or cummins.
  4. wahooUSMA

    wahooUSMA New Member

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    I have an 88' 37 Bert with the 550hp engines; and when new I bet it did run very well and like a rocket ship, but under primo conditions, minimal weight (load), and fresh engines. But over time, and with years of bottom paint, mid-life engines, and other added weight/factors, she now runs like a Cessna vs a rocket ship (my boat weighs 33k lbs, not 25k lbs). Don't get me wrong, mine have 1600 hours, run beautifully, w/no smoke, etc., but you will NEVER see those manufactures spec's with Detroits unless you upgrade to the Cummin's. I am currently have some work done on my props by Wilmington Propeller, to help the engines breathe, as well increase fuel burn and hopefully gain some performance. Just my .02, rebuild the current set up and save the money - you'll never get a return on your investment by sinking 75-100k swapping for the Cummins - additionally, the Bert is not a speed demon hull. If you want a go fast convertible, you need to look at a lighter built boat, flatter transom, such as a Luhrs or Ocean, but then the trade off is you'll need a good dentist to put your teeth back in, or you could step up to the new 37 Viking, 35 Bert, or similar, but be prepared to spend 900k to over a million. Good luck and ping me if you want further info!
  5. Breckster

    Breckster Member

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    No interest in the 37 Ocean/Viking or 35 Bert.. nor could I spend that much on a boat used 3 months out of the year. I know my 37 is fairly “light” and really feels good at 27 knots but I’m usually at 24-25 @ 1900-1950. Had thought, going the 550 6v92 might be a realative inexpensive way of obtaining a 27knot cruise?

    Currently, thinking about something a little newer and larger that would fit our wants; 40 Cabo Convertible seems to have all that I’m looking for?

    Thanks for your imputs wahoo.. out of curiosity, what does your boat cruise at? What size wheels? Fuel burn etc... it will be interesting to see if Wilmington prop can find a little “magic” for you.

    Thanks, Breck
  6. wahooUSMA

    wahooUSMA New Member

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    Wheels right now are 25 x 26, but that will be changing. Not sure on the fuel burn. If I cruise around 1650-1700 at 14-15kts, she's pretty reasonable. Bump it up to 1850-2000 at 19-22kts pinned, and she sucks fuel like a shop vac. We are in So. Cal so boating for us is year round, so the props should be done by Christmas - I'll send you a note then. Regarding the Cabo - great boat, fished a 35 Cabo Convertible and a 40 Express many times - but honestly, I'll take my Bert any day of the week. Yeah, the Cabo is faster, better fuel burn and nicer salon, but to be honest, they don't ride nearly as nice or dry as the Bert's do...not to mention the following sea - nothing compares, but that's just my 02. I did a complete restoration on my 37, stripped the interior down to the skins and it's every bit as nice as a new boat. If you go to 'the magnificent Bertram FB page, you can see my interior...https://www.facebook.com/photo.php?...LKvAnz3Be5m4QMkD6qIseQUXUaZK62AtpI5wBvzuiWqww The cover page is our 37 anchored while in Catalina.
  7. Breckster

    Breckster Member

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    Interesting... I’m running stock 25x28’s with my 6v71’s and looking at the online 37 owners manual, my speed(s) RPM, and fuel burn are almost identical to the 6v92 @450hp. High Tide marine, I believe told me, that the 550’s should be swinging 27x29’s. Listening to others about their boats weight, I’m sure mine is on the light side; 24.5-25.5k. My boat sits on the hard about 8-9 months out of the year and I’m not sure if that makes a difference? I have a Pipewelders half tower w/Stamoid cover but the rest of the boat is pretty much how it left Miami 33 years ago. I did strip off all the paint to bare fiberglass and barrier coated then put two layers of Interlux CSC.

    Interesting about the Cabo 40’s ride.. I know my 37 just eats up our chop we get in the Great Lakes beautifully; Boats, much like airplanes are compromises
  8. Trinimax

    Trinimax Senior Member

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    I have fished a good bit on a 37 bert and a 40 cabo express. I would say that the ride of the cabo 40 was better than the 37 bert overall. In a short head sea they were about the same, maybe a slight edge to the cabo. In a beam and folllowing sea, the cabo 40 was better. The cabo 40 with the 715 hp C12 cats does burn a good bit of fuel, but will fast cruise at 30-31 kts and top about 35-36. The convertible should get similar speeds. The main overall difference in rough seas is that the cabo was much quieter than the bert. no interior bangs and rattles. everything in the interior just seems to be put together better. I believe that one of our members PSW has a 40 cabo convertible, he may be able to chime in with some more info

    hope this info helps
  9. Capt J

    Capt J Senior Member

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    The Cabo is far superior in every aspect. Ride, build quality, speed, etc. the Bertram is not even a comparison. A decades (or more) worth of hull design, engine advancement, and one look at cabo’s wiring, and you’re comparing a corvette to a chevette. Not to mention the fact that in 30 years Bertram couldn’t figure out how to use 5200 or core a boat so that ever deck on them didn’t become a water logged sponge.

    550hp 6v92’s don’t stay 550 hp for very long, usually less than 500 hours. Show me a 550hp horse 6v92 boat that hasn’t had 2-3” of pitch taken out of the factory props that they once spun to wot rpms. I feel the 71’s make the same amount of power as the 92s after a few hundred hours. Top that with the fact most 92 owners run their boats 100 rpms or more below normal cruise rpm (1950) because they’re afraid of them grenadine.
  10. PacBlue

    PacBlue Senior Member

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    There must be differences between our Coasts.

    I know CaptJ has referenced in the past the large amount of work GlassTech has received from spongy Bertram cockpit decks, but in all honesty, we have not seen as much of that out West. http://www.glasstech.co/yacht-refit-1.html

    It also struck me as a bit odd when an ex-Bertram employee can make a living repairing re-occurring water intrusion issues on Bertram's decks, what was going on when he was employed at Bertram? Maybe they would not listen to him, and good for him to make it work out on his own. Anyways, it could also be a case of poor Fighting Chair base installations which we do not typically do out West or the combination of the Florida sun and rain, but we have had Bertram 38/42/46 Sport fishers peppered around our boat slips for years and can remember very few issues with soft decks, no more than some of the other well know brands.

    A refitted 37 Bertram is a much better boat than a Cabo 35 for sure, it is just a better all-around offshore boat. Dave Napier designed the 37 Bertram hull as well as the 43 Cabo hull, which some owners on this site have praised their performance in head and following seas. In looking at a Cabo 40 FB, it is a more difficult comparison for Bertram as the Cabo is a current design and the execution stands out. It's faster and has better balance. But there is no knock on a well trimmed 37 Bertram eating up some head seas, they do that fine for most owners.

    Maybe cooler sea water (or fresh water) is the key for Detroit Diesel longevity. We have had Detroit's through 6-71N, 6-71TI's, 6V-92TA's, 8V-92TI's, and we have enjoyed longer intervals between overhauls then some of the numbers you see out East.. Our 38 Blackfin with poorly muffled, noisy as hell 550hp 6V-92TA's had 3300 hours before their second overhaul.
  11. Capt J

    Capt J Senior Member

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    It wasn’t just the cockpit decks on Bertram’s, flybridge decks, forward decks. Perhaps the heat and rain, but really a poor job sealing them, as I rarely and I mean rarely see the same on old hatteras or Vikings and that is usually directly attributed to a poorly sealed add on on them, dinghy chalks not bedded properly, etc.

    It’s probably the air temps on the west coast attributing to more longevity. Cooler/denser air. Cooler sea water temps going through the fuel coolers, inter and after coolers etc.

    I don’t think a 35’ Cabo to 37’ Bertram is a comparison as the 37’ is for sure a bigger boat and more a comparison to a 40’ Cabo. Which is far superior. I’d still take a later 35’ Cabo over a 37’ Bertram. Even an older 35’ as you have no structural or wiring worries with the Cabo. Head sea the Bertram probably does ride better than an early 35’ Cabo, but the Cabo is superior on the beam and aft. Better thought out cockpit as well.
  12. Breckster

    Breckster Member

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    Thank you for your inputs. There is no doubt (in my mind) that cold and fresh water play a large part in my boats (and many Great Lakes boats) condition. I recently looked at a 11 year old Cabo 40 in Florida and my 32 year boat, that rarely sees more than 3 months of “northern sunshine”, had a much nicer “shine” and gelcoat appearance. Once again, there is no doubt had my current boat been in Florida, in the continues sunshine for the same amount of time that the 40 had seen, it would be not in as nice of shape.

    I would say.. the general consensus is: DO NOT put 6v92’s in for any “gains” for it will only be short-lived, if at all and a complete waste of money. When required, rebuild and maintain my 6v71’s and be very happy w/my current performance or purchase some more modern boat ie Cabo 40, 43, etc...
  13. wahooUSMA

    wahooUSMA New Member

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    Thanks Pacific Blue for a well written response - I wish there was a 'like' button.
  14. boatpoor

    boatpoor Active Member

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    Just curious, but are you sure your 6 71s need rebuilding? Using oil, smoking, weak? Those are great engines if they're not overpropped.
  15. Breckster

    Breckster Member

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    The guys that “ran the rack” , did the valve adjustment, and cleaned the aftercooler (only one because it looked brand new, he said, ...”wasting my money to do the other”) they also mentioned, “they have a lot of life still in them”.

    Original hours of 1300 since new. I’ve had a turbo that was sucking exhaust, rebuilt “just in case” and since it was off, rebuilt; other than just general maintenance; that’s it.

    I have the ability to purchase some 92’s very inexpensively and rebuild them. Had thought perhaps I would do so over, some day rebuilding the 6v71’s, and with more horsepower and torque. Personally, I don’t like the twin turbo setup that my 71’s have; seems there is always a little leak.... :(
    Last edited: Nov 2, 2018
  16. boatpoor

    boatpoor Active Member

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    Unless they have really been mistreated, they should have a lot of life left in them at 1300 hrs. My current boat has the 6v92 TA's with about 2300 hrs on them and they perform really well and don't give any problems, but given the choice I would take the 671's over the 6v92. My boat is quite a bit heavier than yours and I cruise about 22 knots@ 1900 rpm. I've owned several of both and the 671 is a much better engine.
  17. Breckster

    Breckster Member

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    The 37’s came with 92’s from 87-93 so I know the weight won’t be an issue and I don’t think the QSB’s will have enough torque without some serious gear reducing??

    I have to rebuild my 6v71’s (eventually) and have set of 92’s avail and figured they would be the “easiest” route to take being the they are almost identical to my 71’s.... transmission, eng instr, etc etc..
    Last edited by a moderator: Jul 31, 2019
  18. chesapeake46

    chesapeake46 Senior Member

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    How many hours would you expect to get out of 6V71's as opposed to 92's ?

    I ( mistakenly ? ) thought the 71 series had a longer life span in general.
  19. boatpoor

    boatpoor Active Member

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    It depends on how the engines are configured and operated. I've run 671's well over 10,000 hours in the naturally aspirated version and 692's almost as long, but when you start squeezing more horsepower out of them than they were designed for the life span gets much shorter. I know of some 671TIBs that have run for for more than 3000 hours with no issues, but they were well maintained and not over pressured. I can get the same out of 692TAs if I treat them right.
  20. Capt Ralph

    Capt Ralph Senior Member

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    The greatest issue is 71s are more forgiving. Dry liners can take a lot more abuse.
    92s are zero tolerant. No abuse and they can run fine for a long time (chips in hand).

    Next step; High performance; You want to go fast, push the 71s.
    You want to go much faster, push the 92s.
    As any performance enthusiast can tell you, H P robs engine life.

    Now, If you think something warm could be below your feet, Penski did put together a 24V71Ta that blew away the 92s. 16V92 never did develop.
    Last edited: Jul 31, 2019