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Motor Height


shakey55

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Goodmorning FishRaiders. 

 

Took my Seafarer V-Sea (Johnson Oceanpro - 115hp two stroke) for a test yesterday after putting on an SE SPORT 400 hydrofoil that my lovely wife bought me for Christmas. Seeing she bought it, I thought at least I should give it a try.

 

I must say this definitely got this heavy arse boat up on the plane quicker and kept it there at lower revs, it really is a different boat. 

 

Enough dribble, what I did note today was that the best revs I can get out of her is about 5250. 

 

I then had a look while running just above 3000 revs and I think the motor might need to be lifted a hole or two. It is currently in the second hole from the top of 4 holes. 

 

What are the thoughts of the experts. 

 

 

 

 

IMG_2110.mp4

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is your cavitation plate level with the bottom of your hull ?.is your motor leg throwing up spray both sides ?..this subject has been brought up twice recently..raising your motor wont increase your revs .going down a pitch size on your prop will..when travelling go back and check if your new foil is sitting on top of the water or going thru it...rick

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Hi Shakey55,

This will be interesting as I have exactly the same outboard. In saying that, my boat is a Quintrex 5.7mtr allie and I don't think that I have issues getting on plane once I hit the throttle. I just checked my holes and my height is also on the second hole from the top. Will follow to see if you get more out of her if you drop or raise the ouboard.

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2 hours ago, rickmarlin62 said:

is your cavitation plate level with the bottom of your hull ?.is your motor leg throwing up spray both sides ?..this subject has been brought up twice recently..raising your motor wont increase your revs .going down a pitch size on your prop will..when travelling go back and check if your new foil is sitting on top of the water or going thru it...rick

The new hydrofoil is running just under the water (for some reason I can't load the video I have taken) about maybe 1 inch or so.

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3 minutes ago, noelm said:

Lifting a motor that is too low, will raise RPM, what was it like before the foil?

Hi noelm

the addition of the hydrofoil has not really changed the RPM's (maybe a slight reduction if anything).

im not overly concerned, but I'm lead to believe that the motor should be set up so the cavitation plate is level with top of water when trimmed out.  My cavitation plate (now with foil attached) is running about 1 inch or so below the water. 

This is an interesting article I just found

http://www.boats.com/how-to/the-outboard-expert-boost-speed-with-outboard-engine-height-adjustments/

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Hey Shakey, 

I also just purchased the SE SPORT 400 (recommended by Stewy in an older post).

Mine came with the normal circular half indented thingy that sits on the bottom, but it also came with a round rubber washer too. Are we supposed to fit this too? I was unclear on the youtube video they have for this installation.

Dave.

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1 hour ago, The Incredible Hull said:

Hey Shakey, 

I also just purchased the SE SPORT 400 (recommended by Stewy in an older post).

Mine came with the normal circular half indented thingy that sits on the bottom, but it also came with a round rubber washer too. Are we supposed to fit this too? I was unclear on the youtube video they have for this installation.

Dave.

Hi Dave

Put the bolts through (thread underneath) then the rubber washer, then the plastic disc and tighten nut. 

I'll look over weekend and see if I still have instructions. 

If your still unsure let me know and I'll type out detailed instructions from memory. It's easy

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Don't get me wrong fellas, I'm not unhappy with performance, I just think that the cavitation plate should be running higher and I could get a little more out of her 

I'm going to raise it one or two holes and see what happens, but not in a position to do this until end of March as I'm going on a couple of trips between now and then. 

 

Ill check prop prop size over the weekend

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Ok guys, it's a antiventilation plate, not a cavitation plate!  Your AV plate should only be getting splashed when running, not in the water.  Your engine rpm's will increase as height is increased, as drag is reduced, therefore load is reduced allowing the engine to operate with less load and more efficiency. You want your RPM's 200rpm off the manufacturers stated maximum rpm, eg if max is 6000rpm you want 5800rpm loaded. This will give you the best all round proformance and longevity of your outboard. 

If you feel the need to bolt any foils, permatrims etc to your outboard something else is wrong. They only hide the symptoms of other problems and increase drag. 

This topic has been done to death on all forums but there is so much wrong information out there because a friend of a friend said to do this or that, be careful which info you choose to run with because you'll end up in trouble. 

FYI, every outboard powered boat I have owned I have lifted the engine and on all of my friends boats we have lifted the engines.  They are all mounted low. 

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On 02/02/2017 at 10:09 PM, shakey55 said:

Hi Dave

Put the bolts through (thread underneath) then the rubber washer, then the plastic disc and tighten nut. 

I'll look over weekend and see if I still have instructions. 

If your still unsure let me know and I'll type out detailed instructions from memory. It's easy

Ah right... I didn't fit the rubber washer and I took the boat out to longy today, lucky it didnt come off! Will put the rubber washers on the weekend thanks mate. FYI so many baby kings outside, we were pulling up 45cm-60cm kings, such a disappointing day after spending so much effort to get live squid.

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  • 8 months later...

I know this topic has been flogged but what is everyones opinion on my motor height?   Could it go a hole or two higher?  The AV plate is approx 40mm below the bottom of the hull.  The upper plate is about 20mm above the bottom.  Still have 3 holes I can go up.

 

Also does anyone know what brand of hydrofoil I have?  Cannot find any markings or labels on it anywhere.

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Cool yeah went for a run yesterday and has the missus take the wheel at cruising speed and the plate is set underwater couldn't even see a dark shadow of where it might be underwater so it needs to come up a bit.  

 

I'll post back on how it goes after I move it.  (Going OS so might be a month or two)  

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  • 1 month later...

 So finally had the engine serviced and raised to the highest setting.  Still looks a tad low but can't go any higher.  Boat now planes at around 16-17 knots and 3900-4000rpm which is a few knots slower and a couple hundred rpm lower which is good. 

 

Getting sprays from the holes that are drilled in the upper ventilation plate.  Is this going to hurt anything?  Water shouldn't be able to spray up into the engine should it?  This was still trimmed in as it was a bit choppy out.  The sprays go away when trimmed out.  

 

 

videocompress-045-20171209_102000.mp4

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