Which engine?

I am designing a 9 metre displacement powercruiser as a personal project. I've worked out that to cruise at 7.5 knots with my displacement of 5.6 tons will require 39 horsepower (at the crankshaft) running at 60%-70% RPM.

In terms of what I'm looking for in an engine, main priorities are physical size (height), weight, reliability, and smoothness (just the usual things ). Price also comes into it, but is less important.

I've identified the Yanmar 3JH4E as a suitable powerplant

http://www.yanmar.com.au/express/Dealer/Prodspec/ENGINE PDF/3JH4E_TechData.pdf ,

but thought I'd ask here to see if there were any other options (brands or actual engine models) I should be considering.

 

Kubota has a good reputation and the parts at a tractor dealer are cheaper than the yacht store.

Izzsu is also fine , but in the US anyway, suffer from a lousy importer and low quality marine conversion.

For 40 hp at cruise an 80 to 100 cubic inch displacement , no turbo would work best.

FAST FRED

 

Thanks Fast Fred, I'll check out Isuzu and Kubota - much appreciated for the suggestions.

 

You know Brand, people will advise you of an engine simply because they are familiar with them and --well it seemed ok when they had one. All engines today are pretty well as much good as each other.

However after buying 2 big Yanmars in the Sidney area I would if i ever needed to again, buy from a good dealer. A dealer that will help you and care just a liitte bit. A dealer that didnt delay or pass on questions of concerns you may have. A dealer that will gurantee the engine for its normal duration of warranty even though you fit it yourself. A dealer that will help you with the correct engine mounts and installation procedures before you have fitted them. Yes,-- a dealer like that could sell engines to me again.

 

another option...

I suggest that you look into the BETAMARINE line of engines and tranis. They are based on KUBOTA engines. ...Service/Dealer support is outstanding which is the reason I became a dealer for the brand.

www.betamarine.co.uk

All the best....

 

If you're on a budget , and the boat can be fitted with a dry stack exhaust and keel cooling YOU can simply find a small diesel.

Best source is the local refrigerated truck industry which is awash with used engines with good service life left in them.

The engine will be demonstrated running and OK and should be $300 to $500.

FAST FRED

 

In that power, seems that you have basically 4 engines:

The Yanamar 3JH4 you cited.

The volvo D2 40
http://www.volvo.com/volvopenta/glo...oats/diesel_inboard/d2-40/productbulletin.htm


The kubota V1903 marinisation :
http://www.nannidiesel.com/english/4.195MAIN.htm
http://www.betamarine.co.uk/Midrange/BV1903.htm

The mitsubishi S4L2 marinisations:
http://www.westerbeke.com/products/diesel_engine_detail.cfm?eng=30
http://www.solediesel.com/english/Marine Engines/MINI-44/
http://www.vetus.com/engines/engine_M4.17.cfm

You also have other engines, such as the lombardini LDW 1904 , or marinisation of the Ford XLD 416 / 418, but they are less frequent. and for the Ford, slightly higher power).

 

EC Power Systems in WA, OR, ID CO, & UT have developed a marine engine w/ Orca Marine Cooling Systems for the Kubota D905, D1005 & D1105 engines and are working on developing other systems to marinize Kubota engines for the Pacific Nortwest marine market. Call Craig @ 206-436-6060 or e-mail @ craigj@e-c-co.com for a flyer and purchase options.

 

Before selecting ANY engine go to the mfg web site and look for the Cont rating , the one for 24/7 operation and see if its in the hp range and rpm range you can stand.

The better industrial engines will give this info, the auto conversions will not.

The auto engine conversions are better suited to Ski boats or day boats , not a cruiser.

FF

 

If one of the priority is size (height), probably to fit the engine under a floor, that practically ban automotive converted engines.

Most, if not ALL automotive engines are now overhead camshaft, and will be higher than marine or industrial engines with a lateral camshaft.

One thing interesting to know is how the water injection in the exhaust will be done. Given the kind of engines and the weigth and kind of boat you envisage, the injection point of water in the exhaust will be very low, or even under the waterline (with typical engines listed). I dont think this is correct if you do not want to fill up you exhaust system (and cylinders if one exhaut valve stay open at stop) with sea water.

How do you deal with it ?

 

Most, if not ALL automotive engines are now overhead camshaft, and will be higher than marine or industrial engines with a lateral camshaft.


The "Tier 2" rules for any marine or truck engines now mean most sources for new engines are unfortunatly computer controlled , and most have overhead cams. The Auto takeout like Yannmar use a BELT!! to drive the cam, which could cost the cylinder head when it goes.

FF

 

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The Isuzu 4JB1 marinized by Zenith in Brisbane Australia - excellent in terms of value ,design, material and performance (plus the fact that not too far from Sydney)

 

My money is on the BetaMarine, Literally. I bought mine from George. great engine, Great service.

 

Propeller Calculation

Dear Sir
If you sent me the details of your boat I will calculate to find correct
size of propeller
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