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Old 08-18-2013, 09:04 PM   #41
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Engines seldom wear out they mostly rot away, run every day and used they will go 10X's longer then tied to a dock. If not used then pickle them for storage.
My experience with industrial equipment as well. Plenty of pumps out there with over 50,000 hours of use as just one example. Use it of lose it which is fine with me. I don't buy stuff to leave it collecting dust on a shelf or chained to the dock.
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Old 08-19-2013, 06:40 AM   #42
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< Ask any flight school as to hours they get out of an engine versus a private owned aircraft that gets less then 2 hours a year of use. >

You bet , the T-28s used to learn to carrier Qualify in training were operated at full throttle many many times a day ,day after day, yet had the best record for being operational in the US Navy training command.
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Old 08-19-2013, 06:49 AM   #43
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The twin versus single engine debate will go on for ever. My opinion is that it depends on the boats intended use. If you are marina hopping over short distances you will enjoy the docking benefits of twin engines. If you are going long distances repeatedly the single has definite economic and maintenance advantages.

Again relating to use. When we were in the United States 4 out of 5 trawlers we ran across were twin engine, In our five years in the Caribbean we have yet to run across a non local twin engine trawler less than 60 feet in length.

Of course in the Caribbean 4 out of 5 trawlers have a second wing/ auxiliary engine which serves several functions, docking, get home and spare generator.

As with anything with boats, figure out your intended use and then decide.

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Old 08-19-2013, 08:26 AM   #44
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The twin versus single engine debate will go on for ever. My opinion is that it depends on the boats intended use. If you are marina hopping over short distances you will enjoy the docking benefits of twin engines. If you are going long distances repeatedly the single has definite economic and maintenance advantages.

Again relating to use. When we were in the United States 4 out of 5 trawlers we ran across were twin engine, In our five years in the Caribbean we have yet to run across a non local twin engine trawler less than 60 feet in length.

Of course in the Caribbean 4 out of 5 trawlers have a second wing/ auxiliary engine which serves several functions, docking, get home and spare generator.

As with anything with boats, figure out your intended use and then decide.

Marty
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Old 08-19-2013, 01:31 PM   #45
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There will always be some ways to show that ther'e is one or two advantages of having a single but if you consider most significant differences the twin is clearly a better and more expensive boat. I am speaking of boats w the same amount of power.
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Old 08-19-2013, 03:00 PM   #46
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Better is an elusive concept.....

Without a defining set of parameters...just a fleeting thought of no consequence....

That's why the debate always winds up back at the same place...better for some is not better for others.

Now for some...twins with bow and stern thruster with a get home engine/shaft and both Sea Tow and BoatUS is a good idea.
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Old 08-19-2013, 03:20 PM   #47
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I agree with all twistedtree says here, but the easiest one to deal with is the dripless log water flow. My boat has PSS seals and I simply placed a "T" into each water line and connected a crossover line linking the two. Now either engine can deliver water to the other dripless seal. Normally this is only an issue if traveling more than 7-8 kts, but I added it anyway just to be sure. It was a simple 15 minute job and cost less than $10.
Seems to me this should also be the approach for the tranny cooler. Our velvet drives need the cooling. I think I might well do these mods before heading south in Oct.
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Old 08-19-2013, 03:54 PM   #48
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Heat should not be an issue with free wheeling a Velvet Drive. When I talked to their rep, he didn't think free wheeling was any problem at all on a 10 knot boat. He pointed out that Velvet Drives are designed to be used on sailboats and while under sail free wheel the prop. Granted, some boats have feathering or folding props, but not all. He suggested swapping engines every few hours to keep the hours even and lube the tranny bearings if we were concerned.

Velvet Drives pump the tranny fluid through an external water cooled heat exchanger. If the tranny is free wheeling the pump is not pumping fluid. Reverse engineering it to pump fluid while the tranny is free wheeling might be an engineering challenge?
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Old 08-19-2013, 05:16 PM   #49
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Now for some...twins with bow and stern thruster with a get home engine/shaft and both Sea Tow and BoatUS is a good idea.

Why didn't I think of that. I have always believed in backups. The only topper I have is a fellow I met who because of a last minute back out on a boat sale ended up with two identical boats, named the same and docked next to each other. Talk about spare parts

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Old 08-19-2013, 07:40 PM   #50
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Someone recently posted, not this thread, that they fired up their wing engine, driving a counter turning prop etc, to complement their single when docking etc. Without the advantage of experiencing the system at work, it sounded a good "best of both worlds" idea.
(Oops, posted here too,see #43 supra)
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Old 08-19-2013, 07:45 PM   #51
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Re: velvet drives. My owners manual clearly states that free wheeling is acceptable with these transmissions. And I have.
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Old 08-19-2013, 07:59 PM   #52
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Re: velvet drives. My owners manual clearly states that free wheeling is acceptable with these transmissions. And I have.
The Service Manual for Models 70C and 71 approves freewheeling, qualified by "under sail with the propeller turning,or at trolling speeds with one of two engines shut down".
Trolling speed is fairly slow. Perhaps BW are being cautious.
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Old 08-19-2013, 08:23 PM   #53
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I have always considered trolling speed to be at least 6 knots and more likely up to 8..so I think most trawlers in the mid sized class would be fine.

Bay Pelican...I forgot sails in my last post...just in case all else fails including fuel tanks, etc....


Note...may be worthless but found this...

called Velvet Drive Transmissions/Marine today (864.843.9234) which is no longer a subsidiary of Borg-Warner and was directed to their technical department. The person I spoke to was named Jeff who explained that the transmissions can operate freewheeling safely if the speed is kept under 7-8 knots. My speed with the engine set to 1350 RPM last weekend was 6 knots.
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Old 08-20-2013, 12:06 AM   #54
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Thanks guys good info on the VDs. American Diesel had told me the opposite and frankly I hadn't gotten around to confirming it. I think I'll try the single option. The boat is so much quieter that way.
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Old 08-20-2013, 12:11 AM   #55
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Daddyo,
When running both engines are they well synced?
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Old 08-20-2013, 12:29 AM   #56
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Aren't dual engines for wannabe and allreadybe pilots? ... I wanna see someone handling four throttles for a four-engined boat! Like my Dad did with a B-17 over Germany.
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Old 08-20-2013, 12:43 AM   #57
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Daddyo,
When running both engines are they well synced?
Yes. I sink mine with an inferred tach within two rpm. Regardless of this there is a resonance that is greater then the sum. If I ever re-power ours I will convert her to a single.
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Old 08-20-2013, 02:15 AM   #58
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Someone recently posted, not this thread, that they fired up their wing engine, driving a counter turning prop etc, to complement their single when docking etc. Without the advantage of experiencing the system at work, it sounded a good "best of both worlds" idea.
(Oops, posted here too,see #43 supra)
Bay Pelican's setup is a center line 28" 3 bladed left hand prop which has prop walk in reverse to starboard. Offset to starboard is a27 hp Yanmar driving a small right hand 3 bladed Max prop which has prop walk in reverse to port. The Max prop is automatic feathering. Because of the automatic feathering nature of the Max prop the small wing engine in reverse gives a greater prop walk to port than the main engine does to starboard. Thus it is easier to dock Bay Pelican to port than to starboard.
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Old 08-20-2013, 11:26 AM   #59
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Daddyo if you repower you'll have different engines.

There must be some part of you're hull, struts or other factor that is causing the vibrations of your engines to "excite" a section of the hull bottom, a bulkhead or some other part that has the right/wrong length/mass that naturally resonates to certain vibration frequencies.

Do other people that have the same boat have the same noise "experience"? And what's different about their boat?
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