I posted this on Scream and Fly and thought I might give it a shot here as well. Any help is appreciated.

I have a 2004 28 Skater with 300x's. I currently am running 15x33 (re-worked 34's) labbed Merc 3 blade cleavers, and I am seeing 108 mph at 6100 rpms. This is with 1/2 tanks of fuel, 85 degree's, about 250 lbs of gear and two people in the boat.

It seems like I am leaving a lot of rpm's on the table and I am wondering what other props I should try. I have thought about cutting my current props down to 14.75 to gain some rpms, but I thought I ask on here first and maybe save some time.

Also the CG of the boat seems to be a bit off and was wondering what might help. How much would a race hatch and removing the back seat help? maybe balast tanks in the sponsons? any suggestion would be appreciated.

Chris

What makes you thing the CG is off? How far are your props above the bottom of the boat? Are your motors bolted to the transom or are you on setback plates? You should have no problem turning those props with 300x's. I am turning 15x34 labbed 3 blades on a 28 with 300 promax's (not X's less about 30-40hp per motor) at 6200 with only me and 1/2 tank at 109.2 so far, should be a little left in that. Weight really affects the 28, I have not figured it out exatly but about 1 mph for every 150-200lbs I have been told. I know of about 4 28's with 300x's that are running 120+ and I believe they are running 14 3/4 x 34 3 blades. Adding weight to the front of the boat will help with the boat launching out of the water straight up in the air. I have found that seat time is extremely critical in this boat, and believe me I still have a lot to learn. Also where are you trimming the boat? You should not need any positive trim, at WOT you should be slightly negative. When cruising I run quite a bit of negative trim, the boat does very good in consistent rough water but seems to get out of shape with boat wakes. I normally just slow down no use scarying yourself or others in the boat.

The boat seems to get a little flighty when running through boat wake which sounds like you have the same situation. It seems as though a little weight in the bow might help this problem. Right now I run a little tab when running through boat wake and it seems to help.

I just got off the phone with a good freind that has rigged a lot of boats and I think we determined that the problem with my rpm's / speed are related to prop height. If you measure the height from the bottom of the sponson directly in front of the nose cone they are only about 3/4" above the bottom. I think I need to move them up a hole which would be another 3/4" which would put me at 1.5". The motors are bolted directly to the transom now with the six bolts that it came with from the factory.

The only potential problem I can see with moving the motors up with the current configuration is that I will only be able to use four bolts because I am out of hole for the bottom bolts on the upper part of the bracket. My buddy does not think it will be a problem though because he has rigged similar boats only using four bolts. What do you think? Water pressure would also be a concern, but it sounds like others are running 1.5-1.75 above the bottom woitout problems.

I have been running nuetral trim and will try running negative next time I have it out. I have yet to run positive trim because it feels like it does not want it. I think raising the motors is definitely the first step though.

Thanks for your help, it is all appreciated.

Chris

I am not sure how others have their boats rigged but I am using 6 bolts on both the transom and 6 bolts from my motor to my setback bracket. I would check those bolts quite frequently if you plan to only run 4 bolts. Get some other opinions on that. I run the motors to nuetral to get my rpm up and then touch the trim down a tad when doing WOT runs. You will pick up speed the more you drive it. The first time I drove my boat WOT I could only run 99 on gps and thought something was wrong with the boat.

Thanks for the info. I think a setback bracket may be an easier way for me to go rather than try and raise the motors and keep them on the transom due to the patch work that would have to be done to eliminate the four bolts that would not be used.

What kind of bracket are you running?

That was my reason for adding the bracket. Some will tell you not to run a setback bracket because that is moves the weight of your motors already too much (boat was setup to run 2.5's) back even more. I run on a river where rough water is 2-3 footers. I am running a Detwiler 6" Manual setback plate, it has 3 1/4 inches of vertical rise. You could also run a CMC plate they make a 5.5" manual with 2" vertical rise. I ran in pretty rough water on Sunday and did not notice the boat acting any different other than the props breaking loose more due to them being higher. Do not go with anything more than 5.5 to 6" of setback if you run in any kind of rough water. They make 10 or even 12" setback plates but that is way to much stress on the transom, not to mention the boat will really want to ride bow high. Also stay away from vertical adjustments any higher than 3 1/2 inches, they become weaker when you get to 5 and 6" of vertical travel.

http://www.detwilerjackplates.com/
http://www.cook-mfg.com/

Havasu: You have a pm.

Back at you...

DB,

Thanks for the info I really appreciate it.

You guys nee to contact wayne at
www.madefi.com
He knows the best setup for the 28 with 300's