What engine to marinize

Discussion in 'DIY Marinizing' started by MengWalton, Jul 20, 2011.

  1. MengWalton
    Joined: Jul 2011
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    MengWalton Junior Member

    Hi all,

    I have a few projects on the go...
    Just wondering I have a boat, about 16ft long, it had a old 20hp outboard on the back that ive decided to put in my project shed as the points system is completely knackered, I want to drop a diesel engine in the back and have a surface drive, its a speed boat why not! so im after a popular engine to marinize (take the fact that I live in the UK and its MUCH MUCH cheaper to do this than to buy a marine engine, or even a second hand one, good look finding a cheap one) im going to RAW cool the engine and fit marine grade altenator/starter etc. just wondered if there were any suggestions, popular smallish engines, also most new engines have a ECU, I know this creates many problems so I was wondering how old does the engine have to be, for instance a '95 astra isuzu 1.7 turbo diesel, not sure if this has a ECU or not..... Mabie I should steal a generator engine from my ship next time im on :p although Its prob the same size as my dam boat. :p

    Thanks lads
    John
     
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  2. gonzo
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    gonzo Senior Member

    If the boat was rated for 20 HP, the engine you mention will overpower the boat.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    A diesel will be considerably heavier then your old, likely 2 stroke outboard. This alone may shoot the balloon down, but the first thing you need to do is establish how much power your hull can handle. What is the width of the transom and is 16' exactly how long the boat is?

    Assuming you have a 16' long boat with a 5' wide transom you can hang as much as 65 HP outboard on her (maximum), though again, the weight issue comes up as well as other issues such as over powering the boat in all but glass smooth conditions.

    Lastly, some hulls aren't well suited to jet drive setups, so the hull shape is a consideration as well. In short there's a lot of i's and t's that need to be dotted and crossed before you should start buying parts. For additional help you'll have to provide much more information about your boat. Lets start with the year, make, model, weight, how it's setup, general hull shape, deadrise at the transom, etc.
     
  4. CDK
    Joined: Aug 2007
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    CDK retired engineer

    A 16 ft hull, the outboard replaced with a raw water cooled Astra turbo diesel and a surface drive....
    We've seen weirder projects here, but it does qualify for the "dumb idea award".

    Repair your outboard or buy a used one on Ebay instead of wasting part of your life and lots of money in a project you'll eventually abandon.
     
  5. IMP-ish
    Joined: Jan 2011
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    IMP-ish powerboater

    What are you looking at for the surface drive?
     
  6. MengWalton
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    MengWalton Junior Member

    Oh reli, would a 1.1 L petrol be better or do I want to be looking smaller 600cc etc. , I only chose diesel as I know what im doing with them. (as for the outboard , the points system is destroyed, bolts are rounded off/snapped off, theres no make or model on the plate, that makes 3 I own im unable to identify it came with the boat but I never intended to use it, I always wanted a inboard)..... as for the weight issue I honestly don't think there will be one, there is what looks like a old engine drop down in the hull with 2 rails running down either side witch I removed because they were rusted beyond any-hope of repair. the boat measures: 16' long, 6' wide, rise at the transom is 3', it is deep V in shape at the moment I have one seat in the front with the 12v battery, radio and other electrics ive wired up. I could take some photos if that would help.
    CDK: It wouldn't be much of a project if I just bought a outboard and put it on :) , the engine I mentioned was just a suggestion, you have much experience in marinizing engines and I appreciate your input and I look forward to the helpful suggestions your about to make.....

    Thanks for you opinions
    John
     
  7. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    My last 16 ft had a 90 HP Johnsone V4 on it and if its old there will be no rating plate on it and in the UK there are no water police its just what you tell the insurance ....Quite where you intend to use it I am not sure as the speed limit in that sad country is 4 mph or 6 KPH almost everywhere . A good 2 litre diesel often fitted to landrovers is the Montego/Mistro 2 l ..no electronics ....cheap to buy
     
  8. MengWalton
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    MengWalton Junior Member

    Thanks mate, good to know it's not stupid idea, the inland speed limit is 5knts however as soon as you leave inland waterways there Is no speed limit except harbours :)
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If it's a deep V hull you're probably not going to be able to employ a jet drive setup, without huge changes to the hull's bottom. I also find it very hard to believe your transom is half of the maximum beam and you answer about the boat's weight is quite baffling. Considering your experience level (based on your questions and supplied answers), I'd strongly recommend you just go find an outboard and hang it on the boat's butt and be done with it.
     
  10. MengWalton
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    MengWalton Junior Member

    Par: I never said anything about a jet drive?? I was planning on running a shaft out the back as low as possible and put a 1.3L diesel engine attached direct drive using at lowish revs, as for the weight I was simply saying it looks like someone has fitted an engine before, the transom is about 3' there were rough its more like 2 and a half, as for my experience level, with marination of engines your correct im a complete beginner but you have to start somewhere as for marine engineering well that's my career Im a merchant naval marine engineering officer 2nd class (2nd Engineer) . I realise that you didn't know this when writing that post but I do know my way around a boat, admittedly not this small but I have a pretty good idea, I could take ordinates at equal length along the hull and use Simpson's rules and theory to calculate all the LCB, GM etc. however im not going to that extent on such a project. PLUS its been a long time since iv'e had to do any calculations like that think there lost in the Pub somewhere :D....

    Back to topic, im planning to use a small 1 L engine to power a 16' boat Deep V, possibly with surface drive however this is not certain I came here for advice, I AM fitting a inboard marinized engine, I would just like suggestions for this, please don't suggest an outboard as this is suppose to be a project boat.

    Many Thanks
    John
     
  11. pistnbroke
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    pistnbroke I try

    maybe 1 litre a bit small ...my 16ft had a 1.7lite 2 stroke ..go for the montego lump ...you can always turn it down but you carnt turn a 1 litre into a 2 litre
     
  12. CDK
    Joined: Aug 2007
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    CDK retired engineer

  13. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    Cheap you jest .....this bloke is talking about buying a whole Mistro Van for £300
     
  14. anthony goodson
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    anthony goodson Senior Member

    Piston has a point the Perkins Prima is readily available from scrapyards in the UK as they were by far the best part of several BL cars and vans both turbo and NA. The stumbling block is the price of a marine manifold. A generic heat exchanger could be used and an oil cooler was standard on the turbo version anyway ,but the manifold has to be engine specific. Lancing Marine have them but ,to support PAR's view ,for the price ,you could probably find a secondhand outboard. This is true for most of the small automotive diesels available in the UK VW golf etc. My son-in law has a marinised Prima in his dory, the manifold was fabricated for me in 316 stainless by a very talented friend who was a fabricator in an engineering works. The factory has gone to China and my friend talents are no longer valued in this backward looking country, he retrained to drive a tube train.what a bl@@dy waste .Good luck with your project, keep us informed.
     

  15. MengWalton
    Joined: Jul 2011
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    MengWalton Junior Member

    Ill look into getting a Prima/montego engine, are they perkins engines underneath? see what I can turn up, as for the exhaust manifold im sure I can bribe a fitter to make me one, or a jacket and muffler :) apart from a marine starter and alternator is there anything else I NEED to change, its an open engine bay with ventilation fans at the bottom.

    Thanks
    John
     
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