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Old 12-01-2013, 02:22 PM   #21
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Art- Yep, you make good points. Interesting there is a 34 Tolly laying here in Ketchikan looking as though it has been forgotten. Prior to purchasing our current boat, I had watched this Tolly and gave serious thought to contacting the owner to see if there was interest in selling. At that time as now in my post, the thought of obtaining two small 50-60 HP diesels and converting were on my mind. The 34 Tolly would be a snap to made the swap out. Easy access to the engine area. Easy extraction out the door. Time would not be a large investment. More the instrument panel than the actual mechanical work.
However, I am a single engine advocate for the economics. Hence finding as you stated, a current boat that fits the requirements overrode the desire to seek out the owner of this Tolly.
Thanks for the posting- Always enjoy reading you.
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Old 12-01-2013, 03:55 PM   #22
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The 454 gas most likely has a 1:5/1 or 2:-1 gear ratio.and a WOT of 4000 RPM.
Theoretically they could run at WOT however nobody would as they would in a short time be stressed to destruction.[/B][/I][/COLOR]
Al, the 454 (7.4l) Chevy block is a tough motor. Top rpm is really closer to 4400-4600, they can easily run 3800-4000 all day long. Fuel usage at those rpm's as you can imagine is about 20gph or more. We had a 454 single engine 30' Bayliner flybridge, did hundreds of hours on it with no issues. We would regularly run at 3800 with no self destruction.

Our Bayliner:

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Old 12-01-2013, 05:00 PM   #23
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Can you do it in your backyard? Even if you DID do it, the 100's upon 100's of hours it would take would rack up a hellacious yard bill.
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Old 12-01-2013, 05:25 PM   #24
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Can you do it in your backyard? Even if you DID do it, the 100's upon 100's of hours it would take would rack up a hellacious yard bill.
I have the room to comfortably work on a 38'er in mine(yes I've measured and priced transport costs too). In concept it sounds like a great plan, relatively easy even(definitely not overly technical for a competent DIY'er). The reality is the yard bill and never ending details kill it for the average DIY'er. Underestimating total time required is a popular way to rationalize trying it out.

The number of failed project boats I've seen as well as talking to owner/builders helped me suss this out. A real catch is that many only plan to be in the yard until it can float only to realize marinas don't want incomplete projects floating in their berths uninsured. Try getting insurance on an unfinished boat is what I was told by several amateur builders.

The only "real and viable" option to do a project of this nature "economically" is to have your own yard storage conveniently available IMO. That or be prepared to pay a large yard bill. Don't forget DIY yards can be rare as unicorn crap in many areas. Many of the ones that do exist often insist you purchase all material from them.

Some random thoughts from someone considering a similar project.
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Old 12-01-2013, 05:40 PM   #25
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That bloody generator by itself, new, would cost more than $14k in Australia
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Old 12-01-2013, 08:43 PM   #26
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Forgive me for I didn't rationalize the "America" part of the equalizing. Yep you folks have rationalize the issue correctly. I have visited several boat yards in the Seattle area as a curious sightseer. Came away shaking my head at the built in constrictions regarding supply purchases, yard storage fees, insurance coverage required by yards, access to the yard other than working hours, and the list goes on. Not so much up here.
I agree under those conditions the concept is worthless.

short sighted apologies extended,
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Old 12-01-2013, 08:55 PM   #27
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Forgive me for I didn't rationalize the "America" part of the equalizing. Yep you folks have rationalize the issue correctly. I have visited several boat yards in the Seattle area as a curious sightseer. Came away shaking my head at the built in constrictions regarding supply purchases, yard storage fees, insurance coverage required by yards, access to the yard other than working hours, and the list goes on. Not so much up here.
I agree under those conditions the concept is worthless.

short sighted apologies extended,
Al
Land of the free.
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Old 12-02-2013, 12:15 AM   #28
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Land of the free.
Errr... Don, don't you mean Land Of The Fee!!
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Old 12-02-2013, 06:11 AM   #29
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Working on a big boat in a back yard may sound fine , but it SUCKS!

Every minor thing requires yet another trip up and down a ladder (or staircase) and it gets really old after a short while.

A slip at your home work place saves a huge PIA,,,,,,BTDT.
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Old 12-02-2013, 08:36 AM   #30
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Errr... Don, don't you mean Land Of The Fee!!
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Old 12-02-2013, 09:39 AM   #31
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I love this thread! I find the concept intriguing and possibly viable with serendipity!

I had a 30 foot wooden boat years ago with an ailing gas motor. I picked up a Perkins 4-107 dirt cheap. The boat was docked on the Gables Waterway behind a house - access was through the property owners boat house.

We pulled the gas engine and got it to the street. Got the Perkins to the boat. And then the project stalled. Other demands were made on our time. We ended up selling the boat and the new motto as is, where is.

Another time, I had a wooden sloop that needed both reframing and repowering. I got a single cylinder gas motor at a yard sale. We parked the boat in my friends back yard. Steam bent frames in place. And... halfway done, the project lingered till his wide said to get rid of it. Sold, as is, where is, too.

Last story: my wife's 18' Donzi needed repowering. I purchased a bench tested Volvo 5.7L, virtually new. The bell housing nor the exhaust manifold mated up to the original transom shield. Hater much cobbling of old parts from the original motor to the new, we finally got the motor installed. Success! This fall I went through the same machinations with the stern drive.

Moral to these stories? If you start off with a doable project AND have the skills, resources and most important, the will, you can finish the project before your wife calls the trash removers!
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Old 12-02-2013, 09:55 AM   #32
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Moral to these stories? If you start off with a doable project AND have the skills, resources and most important, the will, you can finish the project before your wife calls the trash removers!
Perfect!
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Old 12-02-2013, 10:45 AM   #33
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My vision/pipedream takes an existing twin (45'ish overpowered mid-90's fast trawlers come to mind) and swaps in a single centerline diesel with a splitter "chainbox" driving the two existing prop transmissions. There is, of course, a company that has designed and marketed a splitter gear drive system, but I find their three gearboxes and associated shafting too complex. A more robust and elegant solution is an enclosed, pressure lubed, silent chain drive system. Ramsey Silent Chain (www.ramseychain.com) has actually designed such a system for a Navy prototype (four Yanmar diesels driving two props), and another for a private motoryacht (one engine to two props). A centerline V8 or a large turbo 4 would be the engine of choice for 35-45 foot boats as the shorter length frees up space for the chainbox. Ratio changes would be as simple as swapping sprocket sets. Size the horsepower to your needs...mine are slow cruise with potential for occasional semi-plane to 12-13 knots. Keep the dual exhaust if bling is your thing.
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Old 12-02-2013, 11:10 AM   #34
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My vision/pipedream takes an existing twin (45'ish overpowered mid-90's fast trawlers come to mind) and swaps in a single centerline diesel with a splitter "chainbox" driving the two existing prop transmissions. There is, of course, a company that has designed and marketed a splitter gear drive system, but I find their three gearboxes and associated shafting too complex. A more robust and elegant solution is an enclosed, pressure lubed, silent chain drive system. Ramsey Silent Chain (www.ramseychain.com) has actually designed such a system for a Navy prototype (four Yanmar diesels driving two props), and another for a private motoryacht (one engine to two props). A centerline V8 or a large turbo 4 would be the engine of choice for 35-45 foot boats as the shorter length frees up space for the chainbox. Ratio changes would be as simple as swapping sprocket sets. Size the horsepower to your needs...mine are slow cruise with potential for occasional semi-plane to 12-13 knots. Keep the dual exhaust if bling is your thing.
I must be missing something here. Give up the redundancy of twin engines. Double the running gear of a single engine. Two sets of exposed running gear when a single could have it safely in the keel protected by a shoe. The extra drag created by two sets of running gear. Extra complication of the chains and box. Sounds to me like the worst of both worlds.

Seems to me a single with bow and stern thruster could have as good of handling at less complication. Did you ever see a big Jarvis & Newman run with a big single?
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Old 12-02-2013, 11:56 AM   #35
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I must be missing something here. Give up the redundancy of twin engines. Double the running gear of a single engine. Two sets of exposed running gear when a single could have it safely in the keel protected by a shoe. The extra drag created by two sets of running gear. Extra complication of the chains and box. Sounds to me like the worst of both worlds.

Seems to me a single with bow and stern thruster could have as good of handling at less complication. Did you ever see a big Jarvis & Newman run with a big single?
I was expanding on the original premise of a low cost repower of an existing hull to include the 45'+ size range....not a comparison between twins and singles. The hugely overpowered twin fast trawler grouping includes some very nice hulls that are firmly in the dinosaur category and they are not particularly attractive with today's (and tomorrow's) fuel prices. Prices have dropped as a result. Factor in the "miserly" portion of the premise and a single engine swap versus two smaller engines (in an existing twin hull) might make sense over the long haul. Obviously a purpose built single is the ideal if you want a single...but they are few and far between in the 45'+ size range and they sell at a premium.
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Old 12-02-2013, 12:06 PM   #36
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I was expanding on the original premise of a low cost repower of an existing hull to include the 45'+ size range....not a comparison between twins and singles. The hugely overpowered twin fast trawler grouping includes some very nice hulls that are firmly in the dinosaur category and they are not particularly attractive with today's (and tomorrow's) fuel prices. Prices have dropped as a result. Factor in the "miserly" portion of the premise and a single engine swap versus two smaller engines (in an existing twin hull) might make sense over the long haul. Obviously a purpose built single is the ideal if you want a single...but they are few and far between in the 45'+ size range and they sell at a premium.
OK, I got caught up in the mechanics; and forgot the main point. Getting old sucks!
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Old 12-02-2013, 12:31 PM   #37
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Great idea. A LOT of work. I have toyed with this idea myself. Using the existing transmissions and changing the props would save a lot of money.

What about buying a boat with 12V71s and taking out 6 pistons and associated gear. Use the compressor from a 6V71. ???
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Old 12-02-2013, 01:45 PM   #38
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>they are not particularly attractive with today's (and tomorrow's) fuel prices.<

Eventually diesel will again go below $2.00 a gallon , but it will be a while.
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Old 12-02-2013, 04:55 PM   #39
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Quote"Did you ever see a big Jarvis & Newman run with a big single? "

Depends what you call a big single. My JN (46 ft) has a single 8V71 and a friends has a single MAN.
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Old 12-02-2013, 05:20 PM   #40
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Quote"Did you ever see a big Jarvis & Newman run with a big single? "

Depends what you call a big single. My JN (46 ft) has a single 8V71 and a friends has a single MAN.
I've seen them with some big single Cats, and they really moved. You don't necessarily need twins to move 14-16 knots. A good hull and a torquey engine will do it. How do you cruise your 8V71? Great boats.
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