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Engine height ?
http://hpbc.ca/viewtopic.php?f=19&t=3133
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Author:  phillnjack [ October 25th, 2015, 4:51 pm ]
Post subject:  Engine height ?

hi guys
last time out ran the engine at various heights and found whats best when engine on transom.
But now I fancy another go with a jackplate.

what I want to know is, how much to raise the engine when going back 4 inches or 6 inches.
How much height would these setbacks need .

I will not be using any surface piercing props so cannot go mega high just yet, props being used will be standard alloy and an original omc sst (Still looking for a 13.5x22 raker or something else with very good bow lift )

Author:  dubber [ October 25th, 2015, 7:19 pm ]
Post subject:  Re: Engine height ?

It is all Voodoo. A jack plate with setback changes your centre of gravity. Do what you did before on the transom and play around with it.

Author:  Northbase [ October 25th, 2015, 7:40 pm ]
Post subject:  Re: Engine height ?

Do you have low water pick ups?
Water pressure & temp gauges?
If ya do, start jackin it up till you start going slower or the handling gets squirly.
Keep an eye on pressure & temp as you go up.
If you're running stock water intake and running without gauges......
Go up a bit at a time and start buying parts.
Every hull / motor combo and setup reacts differently to increased setback.
Post a video of it running if you can.

Author:  phillnjack [ October 25th, 2015, 8:23 pm ]
Post subject:  Re: Engine height ?

water pressure is not a problem.
I do only have the stock water intakes on the side of the gearbox, but when I jacked it all the way up
it stayed the same as when down , very good water pressure that did surprise me to be honest.
I also extended and put the tell tale just beside where I sit so I could see if any problems arose.
temp obviously stayed nice too.

I will be trying with a normal sst prop just to see if I get any gains.
If I see any sort of speed gains or any bow lift I can then get a prop to suit.
The prop I will mainly be using grips good and gives low slippage (3.5%) when engine is
bolted direct to transom.
this is not meant to run surface, hope to be getting a raker over the winter and possibly
see better results. prop I am after will be 13.5 x22.

I will be taking video of it the next time out, also video of the anti-cav plate while running to see
what is going on back there..

what are the downsides to having a jackplate that I can expect ?

once I get a video of it I wilkl post and you guys can help me see what to do next.

Author:  dubber [ October 28th, 2015, 9:31 pm ]
Post subject:  Re: Engine height ?

Downside to jackplates? Possibly if the transom was weak it could add stress to it by hanging the motor out further thus changing the centre of gravity. The downside would then be a motor on the bottom of the lake and the boat following very soon after.

Author:  phillnjack [ October 29th, 2015, 6:45 pm ]
Post subject:  Re: Engine height ?

what I want to know is things like holeshot , is this supposed to be better or worse when using a fixed jack plate ?
is a jack plate purely for top speed ? or is cruising any better with them ?

I have no worry's about shallow water benefit as I don't do shallow water if possible.

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