Boat info needed

Discussion in 'Boatbuilding' started by Black pearl, Oct 8, 2014.

  1. Black pearl
    Joined: Oct 2014
    Posts: 31
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: South africa

    Black pearl Junior Member

    Hi guys

    Im new to the forum,and would like to pick your brains a bit
    I bought this boat called a ALFA 24 PS with a Berkeley jet drive,im planning on installing a 351 V8,and restoring the rest of the boat
    Will the 351 have enough power?
    The boat has a alliminium hull and weighs 1,6 tons

    Thank you
     
  2. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Taking a look at a couple of pics and ads for it on the web, it should be more than enough power. The fuel bill could kill you though !
     
  3. Black pearl
    Joined: Oct 2014
    Posts: 31
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: South africa

    Black pearl Junior Member

    Some photos

    Here is some photos
     

    Attached Files:

  4. Black pearl
    Joined: Oct 2014
    Posts: 31
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: South africa

    Black pearl Junior Member

    Mr efficiency
    Whats the smallest V8 i can use? 302?
     
  5. Black pearl
    Joined: Oct 2014
    Posts: 31
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: South africa

    Black pearl Junior Member

    I believe that it use to be a very popular boat
     

    Attached Files:

  6. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Check the model number of your jet drive against it's published specs re hp, rpm etc. If the boat would run with a 110 hp Volvo sterndrive, a 302/jet should do the job power wise, assuming it matches well with whatever the jet drive can gainfully accomodate.
     
  7. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Were there many with jet drive ?
     
  8. Black pearl
    Joined: Oct 2014
    Posts: 31
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: South africa

    Black pearl Junior Member

    I was told that i need 250hp minimum,so i might use a 302 rather,otherwise my fuel bill will kill me
     
  9. Black pearl
    Joined: Oct 2014
    Posts: 31
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: South africa

    Black pearl Junior Member

    I cant get much info on the web,did you see anything on the web?
    The ones i saw didnt have jet drive...
     
  10. Mr Efficiency
    Joined: Oct 2010
    Posts: 8,804
    Likes: 570, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Shallow vee boat should not need 250hp, even allowing for the power hungry nature of jet propulsion. Your boat looks best suited to cruise at 20 knots or thereabouts, so I doubt you need that much. Be guided by what hp you see installed in sterndrive boats, and add maybe 25-30% to that. Jets tend to be more efficient at higher speeds than your boat would be happy at.
     
  11. Jim Caldwell
    Joined: Aug 2013
    Posts: 266
    Likes: 8, Points: 18, Legacy Rep: 48
    Location: Cleveland, Ohio

    Jim Caldwell Senior Member

    The motor MUST match the Jet drive. Get ahold of the manufacture of the Jet drive.
     
  12. Fanie
    Joined: Oct 2007
    Posts: 4,603
    Likes: 170, Points: 63, Legacy Rep: 2484
    Location: Colonial "Sick Africa"

    Fanie Fanie

    How about an outboard... or perhaps two ?
     
  13. Black pearl
    Joined: Oct 2014
    Posts: 31
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: South africa

    Black pearl Junior Member

    Fanie...finances....finances lol
    I want to keep it as original as possible
     
  14. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 474, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    It's all about power verses weight. What does this puppy weigh, full up, with full tank(s) crew, cooler full of beer, etc.? With this, you can work up rudimentary power requirements.

    As I mentioned in your other thread, that jet is designed for modest loads, so best performance will come with 10 - 12 pounds (4.5 - 5.5 kg) per HP, though you'll still get reasonable performance from a 25 pound per HP loading. Assuming you have a 4,000 pound boat (I'm guessing) a 250 HP 302 will offer a 16 pounds per HP ratio, which is going to offer pretty darn good performance. I'd be more comfortable with a 250 HP 351 or a "punched and stroked" 302 (347), so the engine doesn't have to work as hard. Reciprocating mass is a big deal in durability, so asking a 5 liter pump 250 horses is harder than asking a nearly 6 liter to do the same. When you look up Ford 302 marine engines, you'll find most are 190 to 200 HP, yet 351's are 230 to 250 HP and this reciprocating mass thing is the reason. Okay, you can get much more out of these two engines, but from a practical view, the 351 is the better choice and usually cheaper too. Personally, I'd want to save more money and I'd install a Chevy instead, with a 305 producing 200 - 230 HP and a 350 developing on average 230 to 260 HP. If going Chevy, get the LT block (one piece rear main seal) as it's tougher and less likely to leak.
     

  15. Black pearl
    Joined: Oct 2014
    Posts: 31
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: South africa

    Black pearl Junior Member

    It weighs around 1300kg and its got a 200 liter water tank,150 liter fuel tank,crew wil be four people at the most
    And then a cooler box with alot beer!!
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.