Prop Rotation, Hook and a Panther
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Prop Rotation, Hook and a Panther
Been trying to get this 1988 Scarab Panther 30 to run for a couple years. Boat was factory 365 mag bravos. Ended up with 330hp engines. That is when I got it.
Boat ran high fifties to sixty with the 330s and tended to porpoise some. Added some hp to the engines to the tune of 420- 450hp each, non dynoed. Boat woke up a lot, but now did not carry the bow. At WOT the boat was level at best, with a less than loose bow. Seemed the more power I added the more it would stick the bow. Running 27p mirage plus, the boat would do 66mph at 4500rpm, best day. 25p mirages (original) would get 4900rpm and 66.5mph. All speeds gps, props spinning out.
This weekend I did a couple things. 1. I made sure there was no water in the bow. None noted. 2. Checked for hook in the hull... about 1/8" starting 3-4" back from the transom. Not sure what to make of that. 3. Switched prop rotation to spinning in. The result was phenomenal. The boat rose up out of the water all around and ran 68.8 gps with the 27p mirages at 47-4800 rpm. Believe I could hit 70 with more chop. It loved positive trim and would run loose and bow high at WOT. What a blast to drive! I was happy as a pig a sh*t with this, but am not sure I understand why it is working this way.
Last weekend no matter how much trim I added the bow was low and the boat uncomfortable to drive at WOT. Would the hook in the hull cause this problem? If so, I am thinking I need to get rid of the hook in the hull, any thoughts on that. I know many say that is not a good thing to do.
Any input on next steps is welcomed.
Dave
Boat ran high fifties to sixty with the 330s and tended to porpoise some. Added some hp to the engines to the tune of 420- 450hp each, non dynoed. Boat woke up a lot, but now did not carry the bow. At WOT the boat was level at best, with a less than loose bow. Seemed the more power I added the more it would stick the bow. Running 27p mirage plus, the boat would do 66mph at 4500rpm, best day. 25p mirages (original) would get 4900rpm and 66.5mph. All speeds gps, props spinning out.
This weekend I did a couple things. 1. I made sure there was no water in the bow. None noted. 2. Checked for hook in the hull... about 1/8" starting 3-4" back from the transom. Not sure what to make of that. 3. Switched prop rotation to spinning in. The result was phenomenal. The boat rose up out of the water all around and ran 68.8 gps with the 27p mirages at 47-4800 rpm. Believe I could hit 70 with more chop. It loved positive trim and would run loose and bow high at WOT. What a blast to drive! I was happy as a pig a sh*t with this, but am not sure I understand why it is working this way.
Last weekend no matter how much trim I added the bow was low and the boat uncomfortable to drive at WOT. Would the hook in the hull cause this problem? If so, I am thinking I need to get rid of the hook in the hull, any thoughts on that. I know many say that is not a good thing to do.
Any input on next steps is welcomed.
Dave
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Dave it looks like you are on the right track. I don't think 1/8'' over 4' is to bad. But if you straighten it your self it won;t cost much. Where do you run on the bay? I remember back in the day, a scarab with twin 330s and TRS ran high 50s so yours should run a little better with the bravos.
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Try Some Bravo 4 Blade props. They have been known to help carry the bow higher. Rotating inward vs. outward, usually lifts the stern of the boat and can cause unstabilit in some boats. Would use caution if you continue the inward rotation. Inward rotation also has been known to cause slow speed manuevering issues also. The Scarabs were also known to be bow heavy boats. Good riding, but bow heavy. A very good friend has a 34, and she plows the water. Not the fastest, but a good ride. Good luck.
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Thanks for the great insight guys. I think I have the idea now. The boat creates a vee shape in the water, the props are on each side of the vee. When spinning out the wheels try to go up the vee, when spinning in, the try to walk down the vee. The boat was a mega handful at the dock and driving back on the trailer, but I also was trying to drive the with sticks reversed and for some reason my power steering puked the fluid into the bilge during the test, so so power steering. I will test her out again this weekend and decide if I can deal with the boat not wanting to spin on a dime.
I'll tell you what fellas, if this works out, it'll be the cheapest 3mph I ever came across!!
Thanks again,
MMwalters... we run the upper bay from Red Eyes north. I put in in the NE river and can be found in those parts most weekends of the summer. How about you?
Dave
I'll tell you what fellas, if this works out, it'll be the cheapest 3mph I ever came across!!
Thanks again,
MMwalters... we run the upper bay from Red Eyes north. I put in in the NE river and can be found in those parts most weekends of the summer. How about you?
Dave