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  1. #1
    Fleet Admiral Texasmark's Avatar
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    Default Lifting Strakes Function

    Seems to be some confusion as to just what do lifting strakes do?

    Well, obviously, any time you increase the thickness of something, you increase the strength. In the case of a strake, you deform the glass mat to get the strake and the strength, but you don't have to pay the price of added weight like if it were solid. So ok, some builders may (do) add them for strength......course, everyone doesn't use them.

    But the real reason is what you see if you look closely at the Avatar of "achris".

    His 20' Bertram is one of the finest offshore boats in the world and has been for many years. Some of the reasons why are clearly evident in that Avatar.

    While there, notice the lowest strake and the spray being deflected off it. Less hull in the water, less drag and with strakes, as you increase speed, these little water skiis help to lift the hull out of the water and reduce drag, plus help to cushion the impact upon reentry after a big wave.

    Personally, I wouldn't have a deep V hull without them.

    My 2c,

    Mark

  2. #2
    DJ
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    Default Re: Lifting Strakes Function

    They also help in slow speed manueverability by lessening the effect of a beam (side) wind and decreasing side "slip".

  3. #3
    Captain MikDee's Avatar
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    Default Re: Lifting Strakes Function

    That Bertram like the famous original "Moppie" was a great design breakthrough from the mid 60's I believe, but IMO strakes don't cushion the impact of anything, they are flat like a flat bottom boat, good for getting up on plane, getting out of the water, and help increase speed, & hole shot, but a deep vee without them is still you're best (softest) riding boat. I found there's a world of difference between my son's 1989' -19' Bayliner Capri bowrider, and my recent (Rare) 1989' -19' Bayliner Capri bowrider Ski Boat model, both with a 125hp Force motors, His struggles to plane with a Doel fin on it, and is slower then mine (35mph), but is smoother riding. Mine with more strakes on the bottom, and I took the Doel fin off, jumps out of the hole, stays on plane easier, and is faster (40mph), but rides harder, especially when it gets choppy out there. According to NADA, my boat is maybe 200lbs lighter also, but that's only like (1 person less), another thing, my boat is low, and you really hafta squat in it (not good for an old timer like me) while his is really comfy. One more thing, I just remembered, his leans a lot more, and a lot easier, then mine. Strakes are what they are, but could be overdone also.
    89'-19' Bayliner Capri Ski boat, with a 125hp Force
    My Previous Boats http://smg.photobucket.com/albums/v2...ee/My%20Boats/
    My motto - Keep It Simple Stupid
    Or It Can Get Real Expensive Later!

  4. #4
    Moderator QC's Avatar
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    Default Re: Lifting Strakes Function

    Strakes do dampen the (re)entry. Sometimes too much and it can cause a rougher ride. Somtimes just right. Depends on degrees of deadrise and other variables too.

  5. #5
    Captain MikDee's Avatar
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    Default Re: Lifting Strakes Function

    Another thing I notice about my boat with the extra strakes, at low speeds, it does not drift to the side, coming into the dock, because of this, it is a bit of a challenge, you hafta make your sweep just right, or you're too close, or too far away, and it's a bear to pull by hand sideways into the dock, or you can just keep going backward, & forward till you finally get it lined up. It's almost like riding on a railroad track,,, going onto the trailer is fun too, Not! But, one good thing is, wind don't affect me much Never had a boat handle like this before, I think the strakes might be overdone on this model,,,lol
    89'-19' Bayliner Capri Ski boat, with a 125hp Force
    My Previous Boats http://smg.photobucket.com/albums/v2...ee/My%20Boats/
    My motto - Keep It Simple Stupid
    Or It Can Get Real Expensive Later!

  6. #6
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    Default Re: Lifting Strakes Function

    All strakes create some lift, however I would not give all of them the "lifting strake" label. Lifting strakes are deliberately angled so that the inner face is horizontal. Thus maximizing the lift. Lifting strakes on steroids may be extra wide for even more lift. A simple strake, with both inner and outer faces the same width, will leave the inner face canted at some angle, not horizontal. You can see these differences on some bowrider designs.

    Kelly Cook

  7. #7
    Fleet Admiral Texasmark's Avatar
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    Default Re: Lifting Strakes Function

    Interesting replies. Agree that reentry depends upon a lot of things. Given that a deep v without them is softer but dives deeper on reentry, something you don't want if you are in rough seas and they are trying to come over the bow. BTDT (had 2 boats with them).

    Never noticed the problems docking which could be just the deep v or that and the strakes.

    No doubt about weight making the ride smoother but that too could put your nose (bow) deeper into oncoming seas than you'd prefer. BTDT too.

    But you have to admit. That Bertram is one fine looking hull and very functional for what it was designed to do. Tain't she pretty!

    My 2c,

    Mark

  8. #8
    Supreme Mariner Silvertip's Avatar
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    Default Re: Lifting Strakes Function

    "Lifting Strakes" are an option on many pontoons these days. Some manufacturers even offer them in two sizes. They do help to get more of the bulk of these floating docks with an outboard out of the water.

  9. #9
    Captain MikDee's Avatar
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    Default Re: Lifting Strakes Function

    Lifting strakes, tell me about them! I have a lot, and very pronounced, on my Bayliner Ski boat, they actually act like little rudders on their deep side edge, keeping the boat firmly in a straight line, because of this, at low speeds the boat does not drift easily to the side, thus requiring driving in a zig, zag, motion when docking, or going on, & off, the trailer. Do you see what I mean now? this happens to be the only shot I have right now with the boat being covered.
    Attached Images Attached Images
    89'-19' Bayliner Capri Ski boat, with a 125hp Force
    My Previous Boats http://smg.photobucket.com/albums/v2...ee/My%20Boats/
    My motto - Keep It Simple Stupid
    Or It Can Get Real Expensive Later!

  10. #10
    Captain MikDee's Avatar
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    Default Re: Lifting Strakes Function

    Talk about looking like a rookie at the dock because of this Of all the boats I've driven over the years, I never had to work so hard at this.
    But, this boat is fast for the horsepower, jumps up on plane, and holds a plane, very well! As it was designed for,,, it also flys,,, out of the water easily on occasion, and is a bit hard riding in the chop, I wonder what she'd do with a 150hp motor on it? because unlike most early (pre 90') Bayliners, the tag says Max. HP 150!
    89'-19' Bayliner Capri Ski boat, with a 125hp Force
    My Previous Boats http://smg.photobucket.com/albums/v2...ee/My%20Boats/
    My motto - Keep It Simple Stupid
    Or It Can Get Real Expensive Later!

  11. #11
    DJ
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    Default Re: Lifting Strakes Function

    Quote Originally Posted by DJ View Post
    They also help in slow speed manueverability by lessening the effect of a beam (side) wind and decreasing side "slip".
    Believe me, you need some. I owned a flat bottom Bay Boat that was difficult to dock. It slipped sideways, uncontrollably, and would "walk" with propeller torque.

  12. #12
    Captain MikDee's Avatar
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    Default Re: Lifting Strakes Function

    This many? This bold? Strakes, I got STRAKES! just look:
    89'-19' Bayliner Capri Ski boat, with a 125hp Force
    My Previous Boats http://smg.photobucket.com/albums/v2...ee/My%20Boats/
    My motto - Keep It Simple Stupid
    Or It Can Get Real Expensive Later!

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