drive height
05-01-2002, 07:58 PM
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drive height
Ok, I got the drive hung today. It looks like the prop shaft is centered on the bottom of the hull. I have an adjustable extension box, but due to the step and rub rail I can only move it 1/2" each way. What are people's opinons as to how well the boat will plane vs. how it will run with this drive height? The application is on a tri hull single step cat. The center sponson is about 1/2" lower than the outer ones.
05-01-2002, 11:38 PM
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Cord that sounds pretty high. If I understand correctly that the propshaft is in line with the hull bottom. I would think it would be hard to plane. A 5 blade prop might be worth a try.
Eric
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05-02-2002, 09:51 AM
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Most cats run with the X up higher then the bottom that is why they suck to get on plane some times. I would just give it a try and see what happens. If you need to you can get one of those spacers.
Jon
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05-02-2002, 10:21 AM
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My experience is with 21 Eliminator O/B and a couple twin engine Chris Cats. Depending on setback and weight distribution, it sounds like you're pretty close. The cris cats ran well even 1"up from the bottom (4 blade cleavers on speedmasters). The eliminator was even higher.
How long is the extension box, what kind of drive? I wouldn't doubt that you could easily run 1-2" up from the bottom with 10" setback, especially with a 4 blade.
Gary
How long is the extension box, what kind of drive? I wouldn't doubt that you could easily run 1-2" up from the bottom with 10" setback, especially with a 4 blade.
Gary
05-02-2002, 11:15 AM
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I would start with it all the way up and bring a saw to cut your rub rail. Depending on what kind of cat, most of the boats bow lift is going to be genetated by air at high speed, so a lot of trim control is not necessary. Keep raising it until it has problems getting on plane or blows out easily. With that much setback and a notched transom (step?), I think you'll want to start at about 1" above the bottom.
Gary
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05-02-2002, 12:02 PM
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Is there a step on the center pod? I agree with Gary with 12" of setback I think you are going to be way low.
I know on the Chris Cat 2" above the bottom is to low without boxes and 4"-6" with 10"-12" set back.
mike
I know on the Chris Cat 2" above the bottom is to low without boxes and 4"-6" with 10"-12" set back.
mike
05-02-2002, 12:43 PM
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Really! The prop shaft can be above the bottom? I'm just trying to picture how the water is flowing off the bottom in order for the prop to bite. Here I was fearing that I'd have to go down an inch!
Katdrvr-yes, the center pod is stepped and notched.
PB-Firehawk said that the gimble was cut for 19.5" x-dim. The boat was originally set up to run a blackhawk and no box. With me using the 2" shortie drive and a box, I have absolutly no idea where that puts me for a x-dim. But I believe that the blackhawk would have been another 5" above my current height.
Katdrvr-yes, the center pod is stepped and notched.
PB-Firehawk said that the gimble was cut for 19.5" x-dim. The boat was originally set up to run a blackhawk and no box. With me using the 2" shortie drive and a box, I have absolutly no idea where that puts me for a x-dim. But I believe that the blackhawk would have been another 5" above my current height.
