37 Bertram 6v92 550HP shaft size

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.

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!

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.

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

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.

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.

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.

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

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

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.

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.