moving up

[bobk]

Is your boat for sale Bobk ?

It is not listed, but I have been giving it serious consideration. We will not be cruising her north any more and so we are wondering if keeping a big boat makes sense. Bottom line is I'm on the fence and could be knocked off with a good offer. I'd be happy to discuss it with any one who is interested.

Bobk

[bobk]

Bob
The 48 is a great option, I especially like the steps from the aft deck to the flybridge. But I think the 48s are powered by 8-92s, which I understand can be more problematic than the 71 series. What are your engines?

My engines are 6V92 rated at 425 HP. These are well below the 1 HP per cubic inch measure and so would be considered to be low load engines. The bad reputation of the 92s comes from their use in sport fish where they are high HP and run on the stops. I'm not aware of an 8v92 in a 48MY. There were some 671 NAs but they are the rare boat.

The life of these engines has been discussed many times here. The best advice is to relate it to fuel burned assuming proper maintenance. Mine have been run at 1000 RPM, making 8.2 knots at 5.5 gph. Historically I average 1.3-1.4 smpg including the generator burn.

Bobk

[bobk]

I'd take. 92 series over a 71 any day. Not just because it's newer technology and larger displacement but usually not run hard in motoryacht.

Bobk puts a lot of time on his engines and maintains them well. I'd not pass over his boat as an option if it's offered for sale. He takes great care of it.

Scott, my DD mechanic sure agrees with you on the 92s. He is certified on many brands and has rebuilt a lot of engines. Just a couple of weeks ago he offered that the 92 is also much easier to rebuild than a 71. I have motor yacht frinds with 671 TIBs who only get 1500 hours between rebuilds.

Bobk

[rtrafford]

Scott, my DD mechanic sure agrees with you on the 92s. He is certified on many brands and has rebuilt a lot of engines. Just a couple of weeks ago he offered that the 92 is also much easier to rebuild than a 71. I have motor yacht frinds with 671 TIBs who only get 1500 hours between rebuilds.

Bobk

I don't think I'll rebuild the 71's next round. I think the cost/benefit falls short of the reward.

[Pascal]

I don't think I'll rebuild the 71's next round. I think the cost/benefit falls short of the reward.

Went thru this decision making..: figure $25k to rebuild each 8V71, another $5 to 7k for the Allisons. For another $15 k I was able to get factory reman C series with new ZFs. All with warranty, lighter and more HP. No brainer

[Chasemmc]

Pascal, In addition to the $15k per side investment, what other costs such as motor mounts, new shafts, wheels, did u encounter?

[krush]

Our GB is powered by Cummins so the 8-71 DDs will be a learning experience.

Question for 53 owners, I understand that a 53 cruises comfortably at 12-15 kts and tops out at 19-21 kts. Running at WOT for any length of time is not good for any engine but how does a 53 with 8-71s like 15 kts? Is that within sustainable parameters? I assume fuel burn at that speed (about 17-1800 rpm?) will be more than what I'm accustomed to with a lighter boat.

Which model cummins is in the GB?

If it was B or C series, you will never reach close to the same fuel born or other enjoyment of the cummins with a detroit.

[rsmith]

92 series are wet liner engines vs dry liners in 71's that means the liner seals are prone to failure due to poor cooling system maintenance overheating or abuse.

[bnoft]

The Cummins are 6bt, 1991 315 hp Diamond Series. Original owner replaced 300 hp Cummins, don't know why.
We cruise at about 1750 rpm= 9+ kts, no flow scan but figure about 5-6 gph. Calm sea and 2300, we roll over the bow wave at 13.5 its, top end 15 at WOT. She isn't built for that and develops a drinking problem above 1800 rpm. Had the bottom blasted and barrier coated this past winter, at 900 rpm she's gliding at 6kts. Really like the Cummins.

[krush]

Really like the Cummins.

Then you really won't like a boat with detroits.