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  1. #31
    Join Date
    Sep 2017
    Location
    Taipei, Taiwan
    Posts
    292

    Default Re: 2 persons vs. 8 persons aboard

    Quote Originally Posted by Rum_Pirate View Post
    The web site states:
    10 passengers 400 hp and Maximum load (People, Gear, Engine) 1340 kg

    A 300hp will weight in around 300kg.

    So 8 people x 70kg = 560kg +300kg engine = 890kg + 80kg (8x10g gear) + 400kg (full fuel 400 L) = 1,340kg

    So you are at the max load (for the 400hp max) BUT using an engine with 75% of max power.

    Other factors:

    What is the pitch of your prop?

    What is the tachometer reading at (Wide Open Throttle) WOT with low load?
    My propeller is 15 x 14 SS Mercury Enertia.

    The RPM is around 5800 at WOT with low load, and was 5500 ~ 5600 with 8 persons aboard.

  2. #32
    Join Date
    Jun 2010
    Posts
    960

    Default Re: 2 persons vs. 8 persons aboard

    Quote Originally Posted by MartynG View Post
    I imagine the number of people or added weight is for the boat builder to decide. Some boat builders may be more optimistic than others.
    Actually they base it upon weight Martin, they assume 75Kg per male and use their own figures for children, more importantly is the need to read the specifications as they may state up to 4 adults with 6 children at a weight of """""""""".
    I am old and wise because i was young and stupid.

  3. #33
    Join Date
    Oct 2007
    Location
    Belgium
    Posts
    4,864

    Default Re: 2 persons vs. 8 persons aboard

    Quote Originally Posted by peterjaw View Post
    Yes, I do feel a lot difference of getting on plane with different number of people aboard.

    So, what did you do to improve? Moving your passengers as close to the bow as possible?
    putting more weight / people on the bow will improve getting on the plane,
    but
    this will dramatically reduce speed,
    moving weight to the back will increase planing speed

    when I was heavy loaded with one of my previous (petrol powered) boats, I asked two people to sit on the bow during acceleration,
    and move to the back at planing speed..

  4. #34
    Join Date
    Mar 2009
    Location
    Tasmania, Australia
    Posts
    4,266

    Default Re: 2 persons vs. 8 persons aboard

    Quote Originally Posted by Rum_Pirate View Post
    The web site states:
    10 passengers 400 hp and Maximum load (People, Gear, Engine) 1340 kg

    A 300hp will weight in around 300kg.

    So 8 people x 70kg = 560kg +300kg engine = 890kg + 80kg (8x10g gear) + 400kg (full fuel 400 L) = 1,340kg

    So you are at the max load (for the 400hp max) BUT using an engine with 75% of max power.

    Other factors:

    What is the pitch of your prop?

    What is the tachometer reading at (Wide Open Throttle) WOT with low load?
    I think you are on the right track RP, a single 300 HP outboard on a full size 28'er with a big/Max load is always going to struggle a bit.
    They say HP sells the boat, but torque is what actually moves it.
    Propping down a couple of inches will help get it up on the plane a little easier, but if it hasn't got the torque throughout the range to drive the extra weight, you won't get performance.

  5. #35
    Join Date
    Aug 2019
    Posts
    2

    Default Re: 2 persons vs. 8 persons aboard

    In my opinion, there is a boat which comes with 2 seater as well as 8 seater and has a same configuration at a minimal budget. If you are looking for something like that, then opt for the beachlander or amphibious category. There are many boat manufacturers who tries to make the customer needs fulfill. As far as I know Ocean Craft Marine is one of those which has a wide range of boats for every needs.

  6. #36
    Join Date
    Dec 2001
    Location
    north ayrshire
    Posts
    438

    Default Re: 2 persons vs. 8 persons aboard

    Seems odd to me that you loose so much speed but a minimal no of revs I think id be looking at a prop with larger diameter & or bigger blade area or maybe 4 blades.

  7. #37
    Join Date
    Sep 2017
    Location
    Taipei, Taiwan
    Posts
    292

    Default Re: 2 persons vs. 8 persons aboard

    Quote Originally Posted by Beamishken View Post
    Seems odd to me that you loose so much speed but a minimal no of revs I think id be looking at a prop with larger diameter & or bigger blade area or maybe 4 blades.
    So that means "tourque", right?

    In fact, I don't have that much chance to take more than 3 persons, so I wonder if I should
    replace my current prop.

  8. #38
    Join Date
    Jan 2009
    Location
    Lochaber
    Posts
    7,145

    Default Re: 2 persons vs. 8 persons aboard

    Could the prop be slipping a bit on the shaft under high load?

  9. #39
    Join Date
    Aug 2009
    Posts
    32

    Default Re: 2 persons vs. 8 persons aboard

    Peter,

    You NEED to look at the propeller that you have on the 300hp Verado !!! You are going to do damage to the engine if you are only getting 5500 WOT. You need to be aiming to be 6200rpm minimum. I have changed my Vensura 19” 4 blade for a 17” Rev4 & I am able to run at 6200/6400rpm WOT & I am getting better fuel economy with the same speed performance.

    All the best CS.

  10. #40
    Join Date
    Sep 2016
    Location
    SoF
    Posts
    9,472

    Default Re: 2 persons vs. 8 persons aboard

    Quote Originally Posted by cstewart37 View Post
    Peter,

    You NEED to look at the propeller that you have on the 300hp Verado !!! You are going to do damage to the engine if you are only getting 5500 WOT. You need to be aiming to be 6200rpm minimum. I have changed my Vensura 19” 4 blade for a 17” Rev4 & I am able to run at 6200/6400rpm WOT & I am getting better fuel economy with the same speed performance.

    All the best CS.
    That seems a bit high to me. I think 6000 is optimum. Have you got any spec that says 6200/6400 ?
    Neither a Leaver or Remainer be

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