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Drive Centerline on Single Engine V

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Old 09-12-2007, 06:29 PM
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possibly the ride quality increased because of the stability inherent with the design of the shorty. maybe you can try a standard length imco to see if it helps.
the set up seems o.k. i might say that the stern jack is addind extra pressure to the gimbal helmut and gimbal over all.

maybe you can test a standard length imco, and stock xr with out the stern jack v.s with and see if you notice handlind and speed increase or decrease.

raising the x may have lost your ability to carry the bow without too agresive of trim.
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Old 09-12-2007, 08:09 PM
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I'll give it a try. Its not as easy as prop testing, frankly it’s a pain in the ass, but it what has to be done.

Could I get the same effect if I try a drive space??? I know the stern jack increased the speed and handling of the boat. If I could I would rather start with spacer first and go from there.

Thanks for all the help.
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Old 09-15-2007, 12:58 AM
  #13  
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Originally Posted by Hot Boat
As stated before I know that the bottom of the boat needs some work and that might be my problem.

But my original question is.... Is the vertical center line of the drive always in center with the horizontal center of the transom???

And if they are off will it cause slip?????


Monstaaa, below are some photos of the boat running a 32 B1 at WOT. It looks to me that it carries the bow but I'm no expert. The boat has a 7 " wide pad on the bottom that starts about the steering collum back. The drive is an Imco 2" lower set at 5 1/2 " below the bottom of the hull, But I have a stern jack that alters my trim angle. It will give me a higher X dimension with lower angles of trim than a normal set up.

I don’t know the CG of the boat. I can tell you that the cabin is for the most part empty. It’s carpeted but it’s been gutted. Most of the weight is to the rear.

In the next few weeks I’m going to do some work to the bottom of the hull, Every time I did some work to the hull the boat rides better.


Pure Energy. already did LOL
Seems like no one really answered the drive center issue - I've never heard of putting a driveline off center to counter engine torque.....I would think it would make "off throttle" lean the other way - towards the weighted side. If yours is indeed off center, that could be an issue. I would think that with the drive off center and perfectly straight, in theory the boat would then want to turn slightly, requiring that the drive be turned slightly to counter-act that, which would then scrub some speed????

I did see a 29 Warlock that had it's cabin stripped out, a bulkhead added, and was setup for F-1 racing(not an F1 boat from the factory) that actually had "free weights" from the gym mounted to the stringer at the rear of the boat on one side to optimize the boats balance against prop torque - kept them from having to use a tab to level boat, and to add weight to the rear for less trim angle needed for bow lift. Boat did run 82 GPS with a stock Merc 500HP, so I'd say the setup worked pretty good for that particular boat.

I do remember racing side by side against a 26 Scarab CV (same bottom/hull as your boat, just without the swim platform and tall deck) at 80 mph and it was standing on it's tail with only the last foot or two of the pad touching the water - he had no problem with bow lift, thats for sure - but that boat is a bit lighter.....

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Old 09-16-2007, 07:49 PM
  #14  
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Thanks Hang Time.

I had a chance to try a 32P Bravo 1. I was able to get some better #'s this time out.

The boat was full of fuel 2 people. We ran 86 @ 5200. I found out I was trimming to high and that’s where the high slip #'s were from.

It seems that I have 16 % slip. I don’t think that’s bad for a 20 year old hull that needs work to the bottom and full of fuel.

My engine builder says I need to be up around 5700 to be at peek HP and I could also go one pulley size smaller on the blower if I wanted.

If I was to send the prop out to get labed and increased boost by 1 psi, smoothed the bottom of the hull and was lighter on fuel, I would hope I should hit my goal of 90 mph
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