B60 performance with 3412’s

Interesting insight. Had a similar challenge post-repower on our B50 with new cats (replaced 8v92) because we were under propped badly - likely due to taking a lot of weight out of the boat. Took 2100 rpm to hit 80% load and amazingly couldn’t hit 100% load even dragging one motor at idle (test performed by Cat’s TC at Greg Poole). We were running 60% range load factors at nearly -1900 rpm cruise if I recall correctly, and while loaded for bear. New Veem interceptors ultimately fixed this and we picked up 2-3 knots and had the load dialed in perfectly. I’m kind of leaning more prop tuning and bottom job, but will pass your valued feedback to the mechanic for his thoughts. Boat ran great, just a lack of speed issue. No smoke.

Should anything more come to mind, please keep the ideas coming !

Door was in fact open, yes.

Really good perspective, thanks guys.

Just as an aside, props weren’t stamped properly for us to confirm size during survey. Seller advised this morning they may have another set, in boxes; if so, we’ll compare the boxed props against other known sistership vessel data with respect to size / performance.

Thinking otherwise, and purely hypothetical, a bottom job might yield a knot and maybe we can find 2 knots within midrange rpm if we get the load numbers up through tuning. I’m not a run it on the pins guy, but I don’t mind running 75-80% load so long as below ~2000 rpm. Fingers crossed.

I’m surprised that there’s so little data readily available on these vessels, despite being around for 20 years. Broker is going to check vessel books for any factory data; he also shared that capt’n comment about speed was when boat was new and being picked up from factory (insert eye roll).

I hear ya, but old(slow)-boat syndrome is 100% not what I'm looking for; I expect a fair amount of mechanical reconditioning with respect to systems and customizing to my standards, all of which can be easily factored into the price and anticipated depreciation.

When the capt'n gives you performance number which is spot on with all other B60's of similar vintage and power, then the boat misses the mark by about 5 knots... And when vessel is (hypothetically) lighter than the others - sans tower / davit, fish gear, etc... It makes you wonder, particularly when it does not hit 100% load at WOT and load factors are very low at traditional cruise RPM's (yep - - I understand this can be a good thing for longevity)... I'm looking for performance that matches other B60's - - or within reason. The disparity is just too great at this point.

Would be happy with 28-30kn cruise between 1800-2000 and a 35kn WOT, which is about 2 knots off spec and other boats.

Our Repowered and Refit B50 is actually a 1988 hull. We've owned her for 10 years this month and yes, all systems are all 'like new' thanks to about 3.5 years in the yard during our ownership. I get it and I'm not doing that again. Also not keen on going back to 20-25kn cruise speeds with performance of thirsty Detroit 8v92's; I'd double the budget on this B60 and go Carolina boat or 2005-ish Viking 61 first (each of which probably also needs work, of course). Speaking of which, custom boats probably carry considerably more variability between hulls than any production boat, no?

BTW, for those following along..Was just told the travel lift weight gauge hasn't been working for quite some time, as per surveyor who has done several boats at that location. Still awaiting formal mechanic's report info / response to follow up questions.

Thank you all again for your feedback. Some really good points being made, providing some further thought and consideration on my part with regard to different elements of this boat. It'll prompt a great convo or two with the professionals we've hired to help inspect her.

Gratefully yours,
-v

Secondaries - just changed. Maybe 2 hours at most.

More facts... We still don't know the prop measurements or confirmed vessel weight, but seller has a set of spare wheels in storage that reportedly came off the boat but not yet reconditioned. Stamped as 32x50 Rolla's. Calls to prop gurus won't bear fruit unless we first know what we're working with and have specific data points. However, one speculated that older wheels which have likely been reconditioned at some point over the last 10, 15 or 20 years can often end up losing some diameter in the process. Some prop shops tend to increase pitch while reconditioning to achieve the appropriate RPM at WOT - - this could potentially lead to the type of performance loss we're seeing. (another fact: I'm beyond my competency here)

I guess with so much invested at this point, rather than walk, we need to now ask the seller to get us wheel measurements and help us identify the missing performance or be faced with accepting a 60' pig of a boat which has a relatively small resale market when economy or fuel prices turn for the worse. IMO, there's enough other small stuff on the vessel w/ 20 years of age and deferred maintenance, I would have to wish them good luck selling her for the top-dollar being sought.

The survey reports have facts that show she needs some considerable TLC beyond routine maintenance; none of which are specifically impacting performance and nor are they deal breakers for me. It's just time, project management and a few buckets of money. I don't think negotiating the survey findings makes sense until we have the performance matter sorted.

Again, I remain grateful for your wealth of knowledge and perspective. THANK YOU to all whom have chimed in.