Jersey Sportfish Repower

[RicM]

The boat is a 42′ 1993 Jersey Dawn III sport fish. The engines are 6-71 TIB’s, 485HP, that have about 1000 hours on them since full rebuilds. They run fine, but they are noisy, dirty, and smelly. It’s a great boat, and my wife and I both love the interior layout and it’s livability. We are now retired and are contemplating the options of running this boat back and forth from RI to FL vs staging it down there and buying something smaller up in RI. One option is to repower, and I am thinking rebuilt QSB’s at 500 HP. Less weight, more power, slightly better efficiency, and less soot and CO. I would appreciate any input, thoughts, stories of your experience. I find that long days on the water are much easier on a boat with less vibration and noise.

Topic

[leonaj99]

Rick good luck in your repower and in making the tough decisions. I just want to emphasize Tony’s comments regarding sub system upgrades/improvements.
Having done a single engine repower myself in the past and having done most of it myself I found an awful lot to do as soon as the old engine was out.
Old thru hulls? Now I have good access so time to install new ones.
Old water system plumbing? Gone and a new system installed with proper angles so it drains for winterizing.
Didn’t like the battery placement so I glassed in new shelves and relocated (battery cable is expensive LOL).
Time for modern raw water strainer and let’s relocate so it’s easy to service.
Now that I have block heaters let’s install a nice electrical outlet with it’s own breaker that’s convenient.
Oh yes, new exhaust hose and custom riser/elbow.

Those are only a few on the list but you get the idea.

[Rob Schepis]

Hmmmmmm……. spend all that dough and do all that work and yes she becomes WAY MORE sociable but need to run the new girls close to the edge to maintain the cruise speed you are already accustomed to……. but yes all projects do come with a budget…

[Tony Athens]

Possible Jersey Repower

Ric,

Sorry for the late comeback on your post.. Just too many things lately..

Anyway, that also gave me some time to re-read your post a few times and after really trying to understand your situation, I believe the QSB 5.9 could give the performance you need if and only if it was set up to burn between 16 & 17 GPH per engine at not less than 3000 RPM.. That would be the upper range of its “cruise HP” capability.. Hopefully with the well over 2000 lbs weight reduction, a pair of high end props, & the proper gear ratio you will get your 19Kts or so at about 2650-2800 RPM.. You need to understand your boat needs 275+ HP per engine to cruise at those speeds and the QSB 5.9 needs to run above 2700 RPM to deliver that HP for cruising…Yes, you would be asking all this engine can give, but you would still be operating within its design capabilities..
As to noise, vibration & harness, you would never look back.. They are very quiet & extremely smooth, especially at you wine & cheese” speed below 10K’s..

If you wanted to have a higher cruise speed option and have the budget, then the QSC 8.3 would be the engine of choice.. Set up right they can cruise at close to 375 HP per engine which should get up in the 21+ knot range for those long runs..

As to cost, much will depend on your own or in-house capabilities ( things you can do yourself)…But regardless, you’ll probably spend between $120,000 & $175,000 by the time the dust settles do a 1st class repower like this IF you manage all right…. Besides just the engines/gears & instruments, replacing Detroit’s will require many sub-system upgrades any you find that as you get “into” the project, you WILL see many others things on the boat that you will want to redo as they seem to present themselves during jobs like this..

Hope this helps..

Tony

[RicM]

Thanks

Thanks Bill. As always this project is driven by the budget to a degree. I am thinking about remanned QSB’s

[Bill Fuller]

I am no expert but I would think that boat would be really nice with a set of wet turbo QSM-11s. I am quite familiar with a 42 Bertram with a set of QSM-11s that does pretty much everything you want to do and does it easily. I think they now have about 15,000 hours on them.

Just my thoughts. Looking forward to what Tony has to say.

Bill F.

[Rob Schepis]

Welcome aboard Ric. Glad to see you here. I fixed the Reposer thingy.

I guess going from that sewing machine of a single Yanmar 6LP to twin DD’s is a tough transition. Have you been aboard any common rail Cummin’s boats? It’ll make you think that your Yanmar 6LP was too loud and smokey…

[RicM]

Repower, I meant REPOWER

Well first of all I don’t see a way to correct the misspelling in the first title? I see the Spell Check doesn’t recognize the word, and changes it to “Reposer”. Unfortunate!

Anyway, in the first scenario, and as we have done it in the past, we will be running the boat up and down the ICW, both inside and off shore when weather permits. The off shore runs tend to be 100-120 NM dashes when the weather permits, 18-20 knots for 6-7 hours. The boat is a planing hull, hard chines, and weighs about 38,000 lbs. The 6-71’s push it about 17-18 knots at 1900 RPM, and that’s where I tend to run it. The boat is propped on the edge and will make 2450-2500RPM at WOT, depending on load. Also, the wife doesn’t like going slow, and although I have tried to convince her that it’s more relaxing to go 8 knots, she gets visibly antsy after an hour at low cruise.

The inside legs are usually done at 8-10 knots. The fuel economy is about .5NM/Gal (36 GPH) on plane, and around 1 NM/Gal at hull speed.

One big issue for me is noise. The current exhaust/muffler system is LOUD. The mufflers are horizontal “glass pac” style fiberglass cylinders. There is also a fair amount of vibration at certain RPM’s. I have worked the shafts, props, and replaced the Ace motor mounts, and DD mechanics have told me that they are quite smooth for 6-71’s, and I may be expecting too much. After a 6-7 hour run it’s REALLY nice to shut them down.

So to answer your question, I think I need/want something in about the same power range. The boat currently sits low in the stern when fuel & water tanks are 3/4 full or more, the boot stripe definitely going downhill toward the stern, i.e. it could loose a little weight in the stern without needing ballast.

[Tony Athens]

Possible Jersey Repower from 6-71's to QSBs or ??

Ric,

The best way you can go about this is to first list your current “real use” of the vessel and what you want to accomplish after the repower.. What the means is really this…

1) what is your need for “speed”– both the long runs when you want to enjoy the journey, and then if & when you need to travel 20-60 miles and do it a at 18-20 Kts or so? That is really Number One and will affect the entire repower cost and engine choice..

2) If you need to travel on plane in the 18-22Kts range at times, then you have no choice than is install enough power to do that, even if you also want to make long runs at what I call the “Wine & Cheese” speed and you are relaxing letting “Capt Auto” drive the boat……………… So yes, that pushes you up to the 450-550 HP range with engines that can “CRUISE at 300-350 HP and do it for hours on end.

So, with that said, tell me more about #1 and #2 and then I’ll will walk you thru the whole way to go about it..

Tony

[Author]

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