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B60 performance with 3412’s

Discussion in 'Bertram Yacht' started by CWV, Aug 1, 2021.

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  1. CWV

    CWV Member

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    Hi All:

    I appreciate the depth and wealth of knowledge members of this site are willing to share. I’ve found myself in a position where I could use some insight.

    We seatrialed a potentially new to us early 2000’s B60 w/ 1400hp cats (2300 original hours). The load and engine data at WOT looked good (94-96% at 2330/2320 temp 185/186), but the boat averaged only 31-32kn on the pins (capt who ran boat since new stated she would hit 37). Cruise rpm “load” was surprisingly very low, which I understand is a good thing for engine life, however the speed numbers at cruise were about 3-4kn less than expected at 1925rpm and 25-26kn (@65% load if I recall correctly). Our current B50 we repowered; it cruises 28-30 and we don’t want to give up the speed given the ground we cover cruising.

    Aside from healthy fuel load, boat was empty. Bottom clean and in pretty good shape. Original 5 blade Props (veem, perhaps?) appeared visibly in good condition. No tower. No tender. Fuel is from Fall 2020. Capt says this boat “likes to cruise 26kn...”.

    At this point, my only comparable data: (1) a buddy boat of same year, Hp, and hours - but which has a tower / tender - and yet performs considerably stronger at cruise and wot; buddy was with us on sea trial. Also, (2) second hand info of older B60 with lower 1300HP cats and no tower - - which reportedly performs similarly to comparable #1, if not better, thanks to effective prop tuning.

    Engine survey not in hand yet, however mechanic found no indication of alignment problems or anything which might rob us from performance. Boat ran clean but simply felt sluggish.

    New Veems isn’t high on the priority list immediately following purchase - but also not out of the question in due time, as is tuning for current wheels at next haul. Internet info is somewhat sparse. Does anyone else have knowledge of what we might expect in terms of rpm load, speed, fuel burn for this model and vintage boat?

    I’m grateful for any words of wisdom or contribution you might offer. Thank you.
    -v
  2. CWV

    CWV Member

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  3. DOCKMASTER

    DOCKMASTER Senior Member

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    Did you run it at 80% load to get a better sense of true cruise speed and fuel burn? Did CAPT say why he cruised at 65% load or offer an opinion of why the boat lost 5 kn on the top end?
    You mention the bottom is clean and props looked good so I'm assuming you hauled for survey? Did you get an approximate weight?
    And lastly, what about the trim tabs? Are they functional? Were they used?
  4. CWV

    CWV Member

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    Yep. Surveyed last Friday. Tabs worked. Two surveyors, one mechanic, a buddy who owns same boat and myself... capt only suggested it could be attributed to “old fuel”, which he stated also had been “treated” - but perhaps if that were the case the load numbers would be lower with low cetane? (Not my area of expertise)

    I was all over the boat during sea trial and relied primarily upon surveyors to gather data. Haven’t gotten the official survey reports with data; and can’t recall tab position although I remember my buddy having a convo with captain about it - - trying to find more speed while we were under-way. Did get a video of WOT run while offshore while outside of inlet.

    Second hand info (opinion) is that the 3412’s seem to like 75% load and 28-29knots in this hull. I’d sure be happy with that but it’s just not there nor even close on this boat.
  5. Capt J

    Capt J Senior Member

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    A friend ran a 2001 60' Bertram tuna tower, 3412's and when new it cruised at 33 knots. The speed loss most likely is the bottom. Were there 15 layers of bottom paint on it? If so, soda blasting it will probably get you 2 knots. Are you sure the computers are still for 1400 HP versions? Were the props ever cut? I ran one CAT 3412 boat that got hit by lightening, they put new computers in, BUT the computers have to be flashed in the boat for the higher HP and the dealer forgot to flash the higher HP tune in them and we had the associated performance issues like you're seeing.

    Old clean fuel , NO. Dirty fuel filters could absolutely cause it. Dirty air filters could cause it, worn turbo's (which are common on 3412's of this vintage) could definately cause a loss in performance. My guess a combination of bottom paint layers, dirty aftercoolers, fuel filters, turbos....... Boats never get faster as they get older.
    Growler and bayoubud like this.
  6. DOCKMASTER

    DOCKMASTER Senior Member

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    Your first post said 25-26 kn at 65% load. Are you saying that at 75% load you don’t pick up another 1-2 kns for 27-28?
    You could always ask seller to put fresh fuel aboard, new fuel and air filters and re- trial?
  7. CWV

    CWV Member

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    Thank you. That’s really solid insight on the computers/ tune. I’d guess there’s a way to check the software version, but can’t imagine that there’s a history of it ever being changed on this boat. I’ll run it past the mechanic to see if he can double check it.

    I do understand turbos were done.

    Sadly, no history on the props, but in 20 years of use, I can’t imagine not having them reworked at some point during ownership. I’m confident that today’s leading prop shops can do a better job with current technology and tooling to dial in the load factor a bit.

    Bottom was actually very clean. It looked to be in pretty good shape paint wise but for sure there’s some buildup, particularly just above the waterline on the sides. I’ll look into this a bit more to see when the last bottom job was performed, if ever.

    Yes, please keep the great insights and feedback coming!
  8. CWV

    CWV Member

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    My logic and the research, what little info there is, tells me we should see 30kn at 75% and 32 at 80% for this boat. Fuel comment from captain does not give me much confidence. ~ 1600g onboard, so dumping and replace is probably a no-go. Fuel filters new. Air filters not bad looking. Mechanic went over them thoroughly.

    BTW, I fell down the rabbit hole of your 18 page repower thread this morning. Impressive! I’d imagine you’re still very happy with the new cats. We just completed a B50 cat repower 13 months ago with c12.9 1000hp... completely changed the boat and she runs like a sports-car. 50% fuel savings at old cruise speed and we’ve seen as much as 37.1kn out of the boat. 10 years with a growing family and we’re just outgrowing it, not to mention with a desire to stretch our cruising pursuits further.
  9. DOCKMASTER

    DOCKMASTER Senior Member

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    Hope you enjoyed the repower thread. Yes, very happy with the new CATs and the NL gens, and really everything else we did. If I knew what I know now and did it all over again I’m not sure I would do anything differently. Certainly nothing major. Just coming up on 100 hrs on the CATs.

    Back to your Bert 60, I doubt new fuel would make much difference, certainly not going to add the numbers your looking for. You may squeeze a little out of props but even that is a crap shoot. Sounds like your propped about right if you make rated power with full fuel and water. How’s the rest of the boat? Is it reasonably priced? If all else is good is the few kns gonna cause you to walk away? Even on longer distance your not talking about much time difference.
  10. CWV

    CWV Member

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    Too soon to say if we’ll walk. Still gathering info. I think it will revolve around seller’s willingness to work towards a resolution and who’s holding the risk. 10-20% performance loss comes at a big cost when it comes to fuel burn / range and the extra distance we might cover on a long travel day (which is not uncommon). A hypothetical 3-5kn loss turns into 30-50 miles in a 10 hour day at sea when we take off, potentially shortening your legs; also, adding an extra hour or 2 to your day can make the difference between having to navigate a unfamiliar port after sunset or enduring poor weather conditions a bit longer.

    Our current boat is all dialed in. About 350 cruising hours on her new cats and more than just a few miles in the past year. She’s served us well and we really don’t want to go backwards in terms of performance (speed / range) at this point.
  11. Pascal

    Pascal Senior Member

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    I don’t see how fuel from last fall would cause this performance issue. That’s only 9 or 10 months old fuel

    If you’re turning rated RPM on the pins but the load is 94/96% it seems to me that s where the problem is. Props may have been de pitched a little bit to turn RPM. Sure it s good for the engines unless that was done to hide an engine weakness but not for performance.

    Did you get a weight in the slings to compare to original specs

    31kts top seems a bit low. Kinda apples and oranges... but I used to run a 70’ skylounge MY with 1400hp 3412Es and it topped at 30.5kts. And Taiwan boats are not known for their high performance...

    I would expect a 60 Bertram to be a lot faster, especially without tower.
  12. CWV

    CWV Member

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    Agreed. Didn’t get the weight. Hoping it’s in the survey report.
  13. Capt Ralph

    Capt Ralph Senior Member

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    Visibly is not the best prop inspection.
    I used to use a rule & welders vice grips to look for deformed blades but even then, it was still some spot checks that were no way hi-tech or proper.
    AND, it is hard finding a real high tech prop shop.
    We have to by-pass local shops and truck ours to Stuart FL.
    If the wheels you are looking at, are not serviced correctly, you may be missing out on the performance you are wondering that is missing.
    Any recent ISO scans on those wheels?

    Any factory specs and trials performance data?
    How much junk (clothes, spares, house fold out couch, mother-in-laws stuff) is on the boat?
  14. Capt Ralph

    Capt Ralph Senior Member

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    I'd beat him up if he did not get the weight. That's SOP.
    Compare that to factory also.
  15. CWV

    CWV Member

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    Yes, 100% agree on having good prop shop. Boat is empty. No scans that I’m aware of but I will ask broker for performance data from delivery since he sold the boat 20myears ago and it’s one owner. Didn’t scan the props because we hauled prior to sea-trial and didn’t expect a performance issue when capt said she runs 37kn... By looking good I meant to clarify no apparent dings dents or scratches in the wheels. ;-)
  16. CWV

    CWV Member

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    I might know a guy who knows a guy who specializes in knee deconstruction. Ha ha j/k
  17. Pascal

    Pascal Senior Member

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    Most of them time prop issues will result in vibrations and minor loss of performance, not 5 or 6 kts.

    2300 hours isn’t much on 3412s BUT it depends on how the boat was run. The cat surveyor should be able to tell you how much fuel was used as Cat uses hours and fuel burn for maintenance schedule. If the 2300 hours were mostly done at 75% the engines may be a bit tired and props could have been adjusted to reach RPM.

    Any smoke on cold start?
  18. CWV

    CWV Member

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    Smoke cleared instantly. Motors sound great. Still pending report, so don’t know gallons used but will ask.
  19. DOCKMASTER

    DOCKMASTER Senior Member

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    I’m still confused by the CAPT comments. So he’s been running this boat for 20 years and said it would do 37 kns then has nothing to say when it only does 32? Was he able to tell you when the 5 kns disappeared? Or at least if it was immediate or over a long period of time? Or at least when was the last time it did 37? Anything helpful?
    bayoubud and Capt Ralph like this.
  20. CWV

    CWV Member

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    Nope. Nada. Exactly.