SoCal Jet Boats
Tech Talk => Hulls => Topic started by: Riverlife_ on July 15, 2014, 05:50:55 AM
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So I have always wondered what angle/degree should my fixed trim tabs be set at? They are original as far as I know, also same question for ride plates, I know it's a little vague but is there a general rule of thumb?
Thanks for any help, my are not adjustable at the moment but I will be looking for some turnbuckles if it's worth it
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Ride plate at 3* up to start, mines at ~2.5* up, (heavy azz daycruiser)
Cav plates/trim tabs will vary depending on load/speed/water conditions (time for a down pedal :thumbup: )
Dan'l
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Mines at 3 up... but have room to add or take away with shims. (aluminum pieces ranging in 1/16, 1/8). I also made a new plate a tad longer to match the length of my aggressor bowl which is 2" longer than a G. Added right angle to the side of plate to ensure a solid plate. At 3 on my hull it keeps the nose from to much lift at wot as well eliminated any porpoise.... results a solid faster pass.
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Yeah I would start with 3* up on the ride plate. Also the cav plates I would start at zero and got from there. I get the most change on my tunnel by cav plate changes.
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have you tried it without the cav plates?
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have you tried it without the cav plates?
i believe them to be original, I've never removed them
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i believe them to be original, I've never removed them
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only reason i ask is if you have a porpoising issue with the hull... the tab is basically a fix, especially with a stern heavy boat like a 18 foot jet boat with little to no weight in the front and a big block at the rear (lots of boats had hooks built into the hull for this reason...) you want it set at an angle just so the porpoising stops. too much angle and you'll kill top end speed and be burying the bow.
id imagine with a diverter you could ditch the plates though and pick up a few mph?
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It's a 19' and it is HEAVY it's a 1970 SleekCraft and is built like a tank, myself 6'2 245 can walk all over the bow and it doesn't even flex, it's a plywood/glass construction.
also no pourposing issues at all but to me the angle on the cavs look to be downward some "creating" hook and they are not adjustable meaning no turnbuckles so, I think I will remove all the stationary rods and make some turnbuckles and get them to 0* and see if it helps. I
'll see what they're actually sitting at tomorrow on the boat
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Not to totally thread jack, but I'm a little confused... I would think the plates or trim tabs would help a diverter. Or at least that's what I was told. Start with a diverter, if it still porpoises get a set or trim tabs, if it hasn't been corrected, get a shoe and ride plate. Then after that for me swap to a split bowl and start trying different attachments.
Am I off, or was I miss lead?
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Not to totally thread jack, but I'm a little confused... I would think the plates or trim tabs would help a diverter. Or at least that's what I was told. Start with a diverter, if it still porpoises get a set or trim tabs, if it hasn't been corrected, get a shoe and ride plate. Then after that for me swap to a split bowl and start trying different attachments.
Am I off, or was I miss lead?
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Depends on what type of porpoise you are experiencing.
Rhythmic bounce after hitting a roller is usually fixed by trim, a constant ass pounding hop is usually a hull issue, a high speed WFO bounce is usually a loading and/or hull defect.
All have different fixes....
GT
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Depends on what type of porpoise you are experiencing.
Rhythmic bounce after hitting a roller is usually fixed by trim, a constant ass pounding hop is usually a hull issue, a high speed WFO bounce is usually a loading and/or hull defect.
All have different fixes....
GT
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I think it's a little of two, I can at a certain speed like 4100-4450 rpm just glide across the water. Faster and I get a bouncing after a wave. Also when I'm all in it I jump out of the water, my little brother told me it's like a foot plus sometimes...
It did get a lot better with the diverter, but it's still there.
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I think it's a little of two, I can at a certain speed like 4100-4450 rpm just glide across the water. Faster and I get a bouncing after a wave. Also when I'm all in it I jump out of the water, my little brother told me it's like a foot plus sometimes...
It did get a lot better with the diverter, but it's still there.
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What do you have for a loader?
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What do you have for a loader?
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Humm.... What came stock on 77 Southwind mini day? I highly doubt it has been changed. I'll have to look into this, never thought that could be an issue. I'll snap a picture when I get over there, currently in storage but trying to get on the water this weekend.
I'm very green to jet boats and first one I've owned, but on the way an had several different water toys. Just never cared for them like this one, used to service it and run it.
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Humm.... What came stock on 77 Southwind mini day? I highly doubt it has been changed. I'll have to look into this, never thought that could be an issue. I'll snap a picture when I get over there, currently in storage but trying to get on the water this weekend.
I'm very green to jet boats and first one I've owned, but on the way an had several different water toys. Just never cared for them like this one, used to service it and run it.
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In the mean time, let me ask you this....
Do the engine RPM's change at all when it get's really gnarly? Like you may be unloading the pump ever so slightly?
GT
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In the mean time, let me ask you this....
Do the engine RPM's change at all when it get's really gnarly? Like you may be unloading the pump ever so slightly?
GT
Yes, when it's really jumping the engine will rev up into a "unloaded" higher rpm. Also I've never really ran this boat in smooth water, I mostly run around on lakes. I know water type makes a difference, I've been around enough water to know it's not handling right but that's about as far as I can go.
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