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Old 12-30-2014, 12:29 AM   #21
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Is the original poster confused because of the multiple ratings? If so please note any given motor in that group of ratings is set for only one WOT HP rating not all. Playing with the motor settings can change that. Modern electronic motors can be changed by a technician on the boat. As Ski pointed out there will be a label on the engine explaining how the factory has set the motor. The settings are usually referred to as M1 through M5 with M1 being most heavy duty full time WOT use and at the other end M5 usually at a higher WOT and HP setting light pleasure use with very little WOT use expected. So when you buy one of these modern motors you get to pick what M setting fits your use and o0n some you can change that to some degree after installation for a price.
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Old 12-30-2014, 12:57 AM   #22
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Eyschulman:

In this case we are speaking to N/A four banger Perkins of 2003 year build.
Pretty simple, nothing dealing with this new technology you speak to. There are horror stories of these new engines creating a flawed electronic little bitty item on re powered fishing boats owned and operated by senior aged commercial fishermen not familiar with the new fangled things ma jigs and are stuck till a technician can rectify the issue. Something to be said for the old ways!! Anyway, this particular application is "Old Boat" stuff.

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Al
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Old 12-30-2014, 07:07 AM   #23
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Something to be said for the old ways!!

You bet , many of the engine MFG are working hard to meet the requirements of the Air Police with improved mechanical injection systems .

The market for repairable engines is HUGE!!
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Old 12-30-2014, 12:22 PM   #24
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Quote:
Originally Posted by Al View Post
Eyschulman:

In this case we are speaking to N/A four banger Perkins of 2003 year build.
Pretty simple, nothing dealing with this new technology you speak to. There are horror stories of these new engines creating a flawed electronic little bitty item on re powered fishing boats owned and operated by senior aged commercial fishermen not familiar with the new fangled things ma jigs and are stuck till a technician can rectify the issue. Something to be said for the old ways!! Anyway, this particular application is "Old Boat" stuff.

Thanks,
Al
what you say is true but that is the way all engines are going. I used to do work and tuning on my boat and car motors when I was younger and did not like all the new fangled stuff like electronic fuel injection that I could not deal with and a full electronic motor is way over my head. But I have to admit the auto industry got it right my modern cars run better and are much more reliable (Chryslers excluded)and fuel efficient than those I could repair myself. The early diesel full electronic motors have had reports of glitches not easily repaired by local mechanics or boat owners not unusual for new technology. I think the diesel engine industry with all its truck motors is getting a handle on the situation and mechanics are starting to come up to speed on the new technology. I now own two full electronic common rail engines and I have to say they do run noticeably much better than anything diesel I have owned before. True there is still plenty of heavy naturally aspirated iron around and they can be kept running longer than most of us will live, but if you buy a new boat you will have to go high tech.
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Old 12-30-2014, 12:33 PM   #25
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Quote:
Originally Posted by Al View Post
Eyschulman:

In this case we are speaking to N/A four banger Perkins of 2003 year build.
Pretty simple, nothing dealing with this new technology you speak to. There are horror stories of these new engines creating a flawed electronic little bitty item on re powered fishing boats owned and operated by senior aged commercial fishermen not familiar with the new fangled things ma jigs and are stuck till a technician can rectify the issue. Something to be said for the old ways!! Anyway, this particular application is "Old Boat" stuff.

Thanks,
Al
The NA old iron are also capable of and have been set to a specific M rating the difference is the factory settings are mechanical in fuel pump and governor etc. The only difference with the newer electronic motors is the settings can be done electronically often with no change of hardware on the boat. An old four banger could be set for higher WOT Rpm and HP or set as a generator with lower WOT HP and RPM. The M ratting and use on an old 4 banger could certainly be sold in three or four configurations and the label on the engine would indicate what it was set at.
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Old 01-01-2015, 07:46 AM   #26
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AL. Confirmation of your intencion, I think your plan are allrigth, keep the 22x15 prop.
plumb. your 4.236 Perkins(a real workhorse!) max. 1800 rpm. (-heavy duty).
This Perkins has a higth TORQUE some 250Nm. and 2400 as low as 1200 rpm.
Your SLO-BELLE will then have a speed around 6.4 -6.5 kts.. at 1600 rpm.and 800 rpm. on propeller, and still have a low fuel intake aabout 1 gall. or 4 litre./pr. hour.
Almost the same speed and fuel consumption, as your former Perkins.
I myself has a trawler, and did exactly the arrangement as you,ll use..! It turn out very well..! Its the TORQUE that turns propeller, - and you have plenty.
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Old 01-01-2015, 07:55 AM   #27
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About TORQUE, sorry NOT 2400 Nm. but 240 Nm. still an heavy turning power.


Wish you ALL a Happy New Year, it has been a pleasure being with you on Trawler site.
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Old 01-01-2015, 05:06 PM   #28
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Thanks Gadenors:

We turn the same shaft and wheel at 2400 RPM (800 RPM at the wheel) with the smaller Perkins and obtain a 6.8. up to 7.3 knot average. As we are retaining the wheel and will be turning the shaft at the same RPM at 1600 RPM with the larger engine all the results should be positive as you have confirmed.

With any project that result in different parimatures this one has them. Now locating the battery bank from the current location to facilitate access to the salt water jabsco pump and starter. In addition to having to run the exhaust out the side as the stern exhaust is "Fixed" and too small a diameter to handle the larger engine.
Then to raise the floor an inch and half to accomidate the new height factor. The good news is all of these can be accomplished without any loss of working space.

Will keep the forum posted as we progress, Will be sometime after this new year for the shop to "Wet" and run the engine to confirm a good purchase.

And a very Happy New Year to you, yours and to all.

Al.
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Old 05-21-2015, 12:42 AM   #29
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To the Forum-

The project to remove a Perkins 4-154 and install a running take out Perkins 4-236 has been accomplished. We launched yesterday and performed a short harbor run to acquire initial results. If you had been involved with this thread you will encounter that a great deal of the discussion revolved around the different results or implication of both using a 2:1 gear retaining the current wheel that was mated with the then 3:1 gear.
We can give the results in total regarding the outcome. First the 2:1 gear mated to the 22x16 wheel proves that we are really over propped. The max WOT RPM is 2000.
However the desired goal was obtained like it was figured. At 1400 RPM we obtain the 6.5 SOG. At 1600 we obtain a close 7 knot SOG.(Hull Speed) When we operated to WOT of 2000 RPM we obtained near 8.6 knots but my God! The fuss behind the boat, the bow up in the air, the noise! There is no cause to exceed the 1600 RPM leaving a 400/500 RPM cushion.

I am going to take the position in prudence and awareness of the over propped situation the results are satisfactory and no engine harm will be resulted to this decisions.

Other opportunities regarding electrical improvement were taken during this installation. We installed a duel bank charging system, a 1500 Watt inverted, a 110 fridge, shifted our battery banks to allow full side engine access.
Of course, as we venture out we will keep the forum apprised.

Al Ketchikan(Bridge to Nowhere)
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Old 05-21-2015, 05:54 AM   #30
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Congrats on completing a fairly involved procedure! Reading your posts, it seems you accomplished what you were looking for. Good Job!
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Old 05-22-2015, 05:17 AM   #31
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Thank for sharing result with os.


Many with a overpower-trawler type boat can learn from AL,s experience.
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Old 05-22-2015, 07:01 AM   #32
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500RPM down from WOT is very safe ,I would consider 1800 to be safe , if you can stand the noise and deck angle.

******
"as M1 through M5 with M1 being most heavy duty full time WOT use and at the other end M5 usually at a higher WOT and HP setting light pleasure use with very little WOT use expected. "

There are RATINGS the engine would be run at , only the speed boat M5 would be at WOT , for a very short time.

The engine at M1 rating will still be capable of more HP and RPM , and many will use the short term ratings to go faster ,make a bridge or lock, , by observing the short time limits , no harm happens.

The propulsion engines are usually identical , the owner chooses the M rating he prefers . to operate at .

Pumps and generators may be set up differently at the factory .
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Old 05-22-2015, 11:20 AM   #33
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Al,
Just take the prop down to the guys in Thomas Basin and have them take off some dia or pitch. One inch of pitch off of my then 18X14 gained 200 - to 250 rpm. If it were mine I'd be think'in of cutting off some dia. 20X16 sounds about right but you can probably rely on the Thomas Basin guys (can't remember their business name) having enough experience to know what is best to do. They've been at it since the 50s haven't they?
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Old 05-27-2015, 10:06 AM   #34
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The boat requires a certain power to go a given speed. Power is related to fuel burn (1 gph is approximately 19-20 hp), so you shouldn't expect much change in your fuel burn. As far as picking the correct prop is concerned, the method is a LOT more complex than the ultra simple Vicprop formula. Ideally you want to be slightly under propped for flat water conditions. That way when things chop up you won't find yourself grossly over propped. I went through this a a few years ago. This link goes through the entire prop choice procedure in perhaps more detail that you want, but it does explain everything.

Repowering Tortuga - Choosing a new Engine
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