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Old 04-22-2021, 11:47 AM   #41
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If I were going for a diesel repower in my boat, I'd swap the 454s for Cummins QSBs most likely. I'd probably end up with similar total power, but more at max continuous. And much lower fuel burn.


Personally, with the 454s, my fast cruise is about 17 kts (3300 rpm / ~30 gph), my slow cruise is around 6.5 - 6.7 kts in flat water (1300 rpm / ~5 gph).
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Old 04-22-2021, 01:13 PM   #42
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I've a friend with the Tolly 45 that had the Crusader gassers. He dropped in a pair of Cummins 5.9s. That made it into a fantastic long distance cruiser. Keep the 45 at 8-9 knots if you're doing long passages, 15 knots will eat a lot of fuel.
Have you idea of the switchover cost?
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Old 04-22-2021, 01:27 PM   #43
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Have you idea of the switchover cost?

I ballparked it on my boat out of curiosity. I came up with somewhere in the $120k range. Figure $80k for a pair of QSB 5.9 remans, new transmissions. Another $10 - 12k for a new generator. Then all of the install related costs. Possibly new shafts and props, although if I went with the 380hp and 1.77:1 reduction ZF280A trans I might not even need a re-prop according to the calculators (and shaft size would be ok as well). And in my case, for the fuel tanks I'd just be drain, clean, inspect and go, as my tanks already have (plugged) return ports in them.

The other good fitting option would be the Yanmar 8LV V8s, but they're likely more expensive (but lighter, they weigh the same as 454s). Costs for your 34 would be a bit lower, as you don't need as much HP and would likely spend a bit less on engines and transmissions.
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Old 04-22-2021, 03:04 PM   #44
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Originally Posted by rslifkin View Post
I ballparked it on my boat out of curiosity. I came up with somewhere in the $120k range. Figure $80k for a pair of QSB 5.9 remans, new transmissions. Another $10 - 12k for a new generator. Then all of the install related costs. Possibly new shafts and props, although if I went with the 380hp and 1.77:1 reduction ZF280A trans I might not even need a re-prop according to the calculators (and shaft size would be ok as well). And in my case, for the fuel tanks I'd just be drain, clean, inspect and go, as my tanks already have (plugged) return ports in them.

The other good fitting option would be the Yanmar 8LV V8s, but they're likely more expensive (but lighter, they weigh the same as 454s). Costs for your 34 would be a bit lower, as you don't need as much HP and would likely spend a bit less on engines and transmissions.
Thanks for providing estimate. Would take a bunch of fuel savings to come anywhere near that "$120K range" of cost!
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Old 04-22-2021, 03:09 PM   #45
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Thanks for providing estimate. Would take a bunch of fuel savings to come anywhere near that "$120K range" of cost!

Agreed. I figured something like 3000 hours assuming 50/50 fast and slow use. But if you wear out some engines or a generator anyway, needing to replace them either way makes the extra cost of the conversion not quite as bad.
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Old 04-22-2021, 06:35 PM   #46
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Yeah, I would love to go with either a 6 cylinder Yanmar or Lugger. I think 10 knots or slower would be fine. Plus more room in the engine room would be ideal.

Really not looking for more power. I just want to keep it simple.

VT
The problem with switching to diesel engines is weight, on top of the costs...
Diesels can weigh lots more than a gas engine, and when you're done, you'll have to re-ballast it to get it back in trim otherwise you'll be stern heavy.

Yanmar's are the smallest and lightest diesels out there, but I consider them shorter hour engines compared to Cats or Cummins, or Luggers (John Deere, etc). I know a guy who bought a pair of remanufactured Cat engines and told the boat mechanic that he wanted to swap out some 454 engines with the bigger Cat engines... The mechanic said "Your boat would sink if you loaded that much weight in there..." Each cat engine was about 4x what a full 454 engine weighed.

So, use it for what it was designed to do and when you're ready for diesels, trade it in for a diesel engine powered boat.
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Old 04-23-2021, 07:31 PM   #47
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Thank you for the input, but I have to disagree on the weights. In addition, Tollycraft 44's did come with diesel engines as an option and I think they are doing just fine ballast wise.

Mercruiser 7.4 liter comes in around 1100 lbs.
3208 Cats V-8 comes in around 1800 lbs. Split the weight in the middle between the 375HP and 450HP models.

The engines themselves sit midship right at the salon windows. That was by design as the windows can be removed and the engines hoisted out.

VT
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Old 04-24-2021, 12:33 AM   #48
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Thank you for the input, but I have to disagree on the weights. In addition, Tollycraft 44's did come with diesel engines as an option and I think they are doing just fine ballast wise.



Mercruiser 7.4 liter comes in around 1100 lbs.

3208 Cats V-8 comes in around 1800 lbs. Split the weight in the middle between the 375HP and 450HP models.



The engines themselves sit midship right at the salon windows. That was by design as the windows can be removed and the engines hoisted out.



VT


Lots of them with heavy diesels. No idea where the notion otherwise came from.
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Old 04-24-2021, 12:46 AM   #49
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Thank you for the input, but I have to disagree on the weights. In addition, Tollycraft 44's did come with diesel engines as an option and I think they are doing just fine ballast wise.

Mercruiser 7.4 liter comes in around 1100 lbs.
3208 Cats V-8 comes in around 1800 lbs. Split the weight in the middle between the 375HP and 450HP models.

The engines themselves sit midship right at the salon windows. That was by design as the windows can be removed and the engines hoisted out.

VT
I didn't say it could not be done, but "You would have to reballast the boat to get it in trim" So, move the engine bunks forward to shift the weight forward, new transmissions, shafting, etc. and them work with ballast to keep it from being stern heavy.
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Old 04-24-2021, 08:09 AM   #50
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For the diesel repower ideas, weight is part of what drove the engine choices I looked at. My gas 454s should be somewhere around 1000 lbs (excluding transmission). A Yanmar 8LV is about the same. A Cummins QSB 5.9 is about 1350 lbs, so 700 lbs more for a pair of them.

Transmission weight is pretty much the same at 150 - 170 lbs for any relevant choice, so I left that out of the comparison. In my case, the existing gas Onan generator is heavy enough that I'd easily be able to replace it at the same or less weight, as only a few similar capacity diesel options are actually heavier.

Even with the heavier Cummins plus whatever ancillary stuff, you'd be adding less than 1000 lbs. That should be pretty manageable.
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Old 04-24-2021, 01:53 PM   #51
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Each of our 1977 Tolly's twin 350 ci, 255 hp Mercruisers weigh 862 lbs. That's only 1,724 power plant pounds for 510 hp. Not too shabby!!

They run perfectly and are good power rating for making our Tolly perform well.

IF - I find need to replace/replenish them. I'd haul both out and rebuild pretty much to specs; with just a bit of upgrades to add a bit more hp. Maybe up to 300 hp. each! My rule of thumb is to never have gas engine's hp. out number its cid. 300 hp. for 350 cid fits well inside those limits. I have a 325 hp. 350 cid in my 1 ton 4wd pickup. She pulls big trailers loaded with backhoe and/or other equipment up steep hills. Two of those powerful 350 cid gassers in our 34' Tolly would make her scream!

Representing my own diy effort; with a bit of hired assistance: I figure [including all the general clean-up and replacement needs that will probably be found in engine compartment] that those twins engines could be hauled out, rebuilt and replaced for somewhere in the range of $13K to $15K... maybe even somewhat lower.

In comparison to $80K to $100K for changing over to [i.e. spending the time and effort to change things over for putting in] diesels... well... there just is NO Comparison!

Happy Boat-Repower Daze!! - Art

PS: About a decade ago ago... on what was then the Tollycraft Forum... I recall posts about a Tolly tri cabin [just like ours] being refurbished stem to stern; including two new diesels. As I recall, the total cost was in the $175K range. Also as I recall having heard - that boat was several years later for sale at $70K. Don't know if it sold. Anyway... You Do The Math!
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Old 05-03-2021, 10:42 AM   #52
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Quick update on the Tolly. Almost got all of the carpet and staples out. Currently doing a template and then look at sanding and filling in some spots on the floor.

My wife did some painting of the walls and its turning out pretty good. We purchased a 11.5 West Marine dinghy and I am configuring it for remote setup. Gratefully the hide a lift davit system works and I am very happy.

VT
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Old 05-03-2021, 12:21 PM   #53
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Great!!
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