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More deadrise on a Sportfish

Discussion in 'Yacht Designers Discussion' started by P46-Curaçao, Dec 6, 2014.

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  1. P46-Curaçao

    P46-Curaçao Senior Member

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    I have a 46ft Post Sportfish, and it’s a pretty wet boat on the mostly rough waters around Curacao, so I was wondering if there is a possibility to create a bigger deadrise, to give it a dryer ride in rough water conditions.

    For example, my former boat was a 31ft Larson Sport Cruiser, with twin stern drives, it was no deep V, so basically it had a very wet ride, but by just trimming the sterndrives up, the spray went more backwards, so I could create a pretty dry ride even on 4-6 ft seas.

    As the 46 Post has no stern drives, are there any options to a create a bigger deadrise?
  2. olderboater

    olderboater Senior Member

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    Trim tabs could be used. I don't know how much they would help but they could be added and used certainly to raise the bow some. Sam principle as trimming the sterndrives. Bennett does offer them for boats in the size range of your post.
  3. P46-Curaçao

    P46-Curaçao Senior Member

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    ...on my boat, I (almost) never use the trim tabs, because they put the bow down...

    [​IMG]
    I only correct if the boat leans a bit to much... (if 13 trays of beer stored on port side)
  4. olderboater

    olderboater Senior Member

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    Obviously the "up" position on yours isn't far enough up to raise the bow higher. Yes, tabs down, bow down and tabs up, bow up. In fact, if all adjustments push your bow too far down, it could be that the tabs themselves and their installation are a source of the problem. That is assuming from your comment that you're running with them all the way up. I've always had tabs where the normal best ride was around mid way so I could adjust up for speed and down to lower the bow.
  5. RT46

    RT46 Senior Member

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    The only thing that may help to make your 46 Post less wet would to be to add spray rails.

    It is my understanding that bow entry and bow flair are the two thing that greatly impact how dry a SF will be.
  6. Capt J

    Capt J Senior Member

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    and weight. If you have a bow tank and a stern tank, drain the bow tank first which will raise the bow and use the tabs to trim it down a bit and you should also get a slightly faster cruise speed. Spray rails help a lot also.
  7. P46-Curaçao

    P46-Curaçao Senior Member

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    Weight could be something to look at Capt J, I have a bow tank (under salon floor) and a stern tank (under cockpit floor), but also stored a lot of tools and beverage stock upfront... (4-500 lbs)

    [​IMG]
    Last edited: Dec 6, 2014
  8. P46-Curaçao

    P46-Curaçao Senior Member

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    RT46, do you know anyone that had real good results with sprayrails on a 46 Post? I read a thread of a Post owner that was not realy satisfied after a lot of work...
  9. olderboater

    olderboater Senior Member

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    Weight would obviously be the simplest area to look at first
  10. P46-Curaçao

    P46-Curaçao Senior Member

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    FYI, Up is flat with the bottom...
  11. Capt J

    Capt J Senior Member

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    Run both motors off of the bow tank and drain that one first and you'll see a noticable benefit in ride and speed..... Then bring the bow down with the tabs as needed (you'll get more stern lift and that's where the additional speed comes into play. When it's just right, switch one motor back to the aft tank......500 lbs in the bow makes a huge difference in the trim on a 46' SF.
  12. P46-Curaçao

    P46-Curaçao Senior Member

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    Ok, after changing my injectors, I will clean out the bow and see what this does, changing the tank configuration needs some planning on parts needed...;)
  13. RT46

    RT46 Senior Member

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    yes I agree weight will help also.
    try to keep the rear tank full.

    If you plan to run both engines off the forward tank you will have to re-route the feed and return lines.
    My Post has a transfer pump that I can move the fuel around between tanks.
  14. Capt J

    Capt J Senior Member

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    IS it plumbed so 1 motor only runs off of each tank? If so, you'd only have to put valves for the motor running off the bow tank......well when you get the fuel down to a 1/3 or 1/2, just top off the aft tank and take it for a quick sea-trial and see how it reacts before spending any money with valves, etc.......Most modern SF, everything draws off of the aft tank and the foward tank has a transfer pump only so you can transfer it to the stern as quickly as you want to.
  15. RT46

    RT46 Senior Member

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    My Post 46 is plumbed so one engine runs of the forward tank and the other runs off the aft tank.
  16. Capt J

    Capt J Senior Member

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    So, then I'd recommend to wait until he gets down to 1/2 or a 1/3 of a tank in both tanks, go to the fuel dock and top off the aft tank only, go for a seatrial and see how the boat performs before spending any money on hoses and valves and such..........then top off both tanks

    I see some builders like Searay use one fuel valve where the return goes to the fuel valve and then you only have a supply hose from each tank. The return doesn't even go to the tank, just the valve.....