35' cat concept for the inside passage.

Discussion in 'Boat Design' started by Boston, Dec 6, 2011.

Thread Status:
Not open for further replies.
  1. Boston

    Boston Previous Member

    OK post 521 my left nut if you'd elaborate on that CP issue and why resistance got worse rather than better.

    I'm at 37' these days and willing to work this here pencil like object if it gets me a better performance curve

    damn
    still out of breath, just got in from an evening run with the dog.
    cheers
    B

    PS
    how the hell did you hit 20 knots in that thing and what HP did you assume????????
     
  2. groper
    Joined: Jun 2011
    Posts: 2,483
    Likes: 144, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    i reckon itll go over 25kts and possibly give 30kts a nudge with the 90hp motors...

    Its displacement is only 3.5 tonnes (fully loaded) and it will have between 140-180hp total installed power (havnt decided yet) so completely different ballgame to your boat... hulls have only 24" waterline beam...

    As to the Cp issue, theres plenty to read if you google "prismatic coefficient speed length ratio" but the results im getting do not agree with the general trend - for the hull shape im using that is... completely different hull shapes, especially those with constant curvature, it may well hold perfectly true... i havnt bothered with any other shapes yet because this one seems to be working so well and is considered more normal for my high speed regime anyway... it was just surprising that it also worked well at low speeds, which was surprising/strange...
     
  3. Boston

    Boston Previous Member

    um I was thinking two motors of ~40 hp each in mine ;-)
     
  4. harry cassin
    Joined: Jan 2012
    Posts: 48
    Likes: 1, Points: 0, Legacy Rep: 28
    Location: Brisbane

    harry cassin Old Salt

    Sweet Ride i reckon :)
     
  5. liki
    Joined: Nov 2008
    Posts: 221
    Likes: 12, Points: 18, Legacy Rep: 114
    Location: Finland

    liki Senior Member

    Boston,

    e.g. ZF25 hydraulic transmission rated for 0.0166kW/rpm continuos duty up to 3200 rpm weights 24kg and costs around 1500 EUR. 1500 EUR and 24kg does not provide much of a split power line for a single engine, I would think.
     
  6. Boston

    Boston Previous Member

    hmmmmm link please. if its only 1500 new then it might just do the trick, but I'll need 2.
    1500 is about my cut off point for it being worth it to just assemble my own

    woops hydrolic ?

    does that mean the gear shift is hydrolic or the power in is hydrolic ???????
     
  7. liki
    Joined: Nov 2008
    Posts: 221
    Likes: 12, Points: 18, Legacy Rep: 114
    Location: Finland

    liki Senior Member

  8. Boston

    Boston Previous Member

    sold
    it seems like the simplest solution for the price, so I'm in

    now to go figure the weight of the shaft and the transfer linkage

    I kinda like the idea of a straight shaft but I'm lost about this particular aspect of the drive train.

    I want no chance of a leak
     
  9. harry cassin
    Joined: Jan 2012
    Posts: 48
    Likes: 1, Points: 0, Legacy Rep: 28
    Location: Brisbane

    harry cassin Old Salt

    What a fantastic website and cheap tranmissions :)
     
  10. Boston

    Boston Previous Member

    goes well with my penny pinching style

    I just hope they don't end up being from China
     
  11. harry cassin
    Joined: Jan 2012
    Posts: 48
    Likes: 1, Points: 0, Legacy Rep: 28
    Location: Brisbane

    harry cassin Old Salt

    You could always send them a email :)
     
  12. WestVanHan
    Joined: Aug 2009
    Posts: 1,373
    Likes: 56, Points: 0, Legacy Rep: 746
    Location: Vancouver

    WestVanHan Not a Senior Member

    If they are not made in China I'd be surprised.

    I bought 3 50 hp rated ones out of Shanghai for a friend ~ 4 years ago..one to use and 2 for spares. 700 hours and the first one is still tight, $200 each and I think shipping was $300.

    Local price for top name was $2200...
     
  13. Boston

    Boston Previous Member

    I'm funny on stuff from China. Haven't had the best of luck with it at all.
     
  14. sabahcat
    Joined: Dec 2008
    Posts: 792
    Likes: 28, Points: 0, Legacy Rep: 273
    Location: australia

    sabahcat Senior Member

    Hows that computer, TV, Fridge, DVDplayer, etc etc etc etc etc going?
     

  15. Boston

    Boston Previous Member

    this next step will take a while, I've got to find a drive line and the shaft through hull weights, at which point I can figure out where it is best to place the stuff. If my COB is adjustable by up to 10% center to aft then I'd be inclined to locate it aft and let the boat sit low forward at rest by a small amount. Hopefully that way when underway it will trim out onto its lines. Or something like that.

    Thing is I'm back to work for a few weeks at least so my time will get a little tighter.

    cheers
    B
     
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.
Thread Status:
Not open for further replies.