I've got Imco +3 boxes. 12 inches setback and 3 inches up. The rule of thumb is one inch up for twelve inches of setback puts you back to "square one". So height wise 12+3 would give the same "bite" as 2" shorties on the transom. Ext boxes give the drive more leverage on the hull.

Formulas are cut for 3" spacers on center rise BBC manifolds for the silent thunder platform. The Brtavo replacement CMI's I have should work with the engines raised 3 inches.

The 311 hull is a good hull and I'm convinced that with filling and block sanding, sharpening the strakes and rear edges, a 12" setback and 3" up will give me a good baseline to start with.

I'm aiming for 750+hp on pump gas and expect to run 90+ after tweaking.

I don't have cones on my XRs and dont plan on using them until I get a feel for how they act with the above setup.

I have no idea when I will get around to this, since I have been "meaning to" for quite a while now.

Hope you don't mind me asking all these questions but I feel like I've found a "well" of information. So, if you are going to raise the motors three inches, I would suppose that means your CMI's are lacking three inches in "height" to line up with the factory "thru hull" holes. How are you going to raise the engine, some time of motor mount extension?

What are you "filling and block sanding" on the hull? Just normal dings and chips, or something more? Also how sharp are you going to modifiy the strakes, mine are in excellent shape but they are not what I would consider "sharp". How sharp is sharp, if that makes any sense? I've always heard that nose cones really don't make much of a difference until you are above the 80 mph mark. Down here there is a real issue of who makes the best ones, Hydromotive or Bob's Nose Cones. I don't have a clue whose is best. I suppose they are both pretty good. I know by swapping out my original Mirage props for Hydromotive's Quad IV's made a hell of a difference in Outlaw. The IMCO extension boxes sound like a real good way to go. Thanks for all the info. I've printed out everything you've told me and putting it in a "make Outlaw faster" file. Thanks.....

Imco makes a +3 Inner bracket. It has all of the rear mounts raised 3 inches. Then all you gotta do is raise the fronts.

Take a look at your current exhaust manifolds. There is a 3" spacer block between the manifold and the riser. If you remove it and raise the motors, you are still using the same holes in the transom. The CMIs should (I haven't test-fitted them) line up once the motors are raised.

The last 6' or so of hull needs to be FLAT. Shoot some flat black paint lightly across the hull and block sand it with 400 paper on a 2x4 stud. It will show the high and low spots.

rough sand the edges of the strakes and rear edges with 180 and apply marinetex. Sand them as sharp as you can, always using a sanding block. Water will run "around the edge" if it has any radius and act as drag.

As far as cones, it matters a LOT on what your x dim is, and what kind of positive trim you must run. On a straight vee, you always need help lifting the nose for less drag, but deep x creates drag even more. So it's a trade off.

Like anything else, there is no way to know what will work best until you have duplicated a setup and tried all the options. I will definitely try a cone at some point, but not until I have done the box and the motor work cause they will change it all. Whether a cone helps now is useless information later.

I know I've been slowed down on outboards when adding cones.

Cool.....My wife see's this project and my ass is toast. Will get to it asap. That black spray paint on the hull is a killer idea. Then just sand it till it's all white. Duhhhh...
Now far up should I fill and sand the strakes or probably best to just do the entire length. Realistically, how much speed gain do you think this will accomplish over a "stock" rounded edge hull. Just curious. Now I'm really getting excited. There's a particular 35 Cafe Racer I'm kind of gunning for.

No, if you got dips bigger than .020" (and you will) then you got to rough them up and fill them with mtex also.

Only worry about the last 6 feet of hull.

anywhere from 1 to 3 mph.

(I've honestly never done a hull over 20', but have seen excellent results on little outboards. You gotta do these big boogers on your back while the little boats, you just flip them over...)

I can't wait to get started. Gotta think of an answer when the wife asks, "now what the **** are you doing, instead of working on the bathroom"?

You can fill with gel and it will match better, but the edges will be weaker. MTex is tougher than gel.

The white won't be a dead match though. Formula gel is not a pure white.

Fairing compound is easier to sand than MTex and can be used in the open areas, but won't hold up to the edges either. I'm not sure if there is white fairing compound, though, cause the stuff I've used is blueish.

On the outboards, we used blue fairing compound on the flats, Mtex on the edges, and then sprayed 2 part polyurethane over it and wetsanded with 600. Left it that finish. On the rear edges, we actually built "lips" on the tail. What I mean is that instead of sanding to match the transom angle, we built it out 1/2" past the transom, block sanded it square and straight, and then put a reverse 45 bit on a router with a pilot bearing and cut a 45 back towards the transom. Ended up with a trailing edge sorta like a 45 degree knife edge.

Ahaa!!! That is what I pretty much pictured. Can you tint Marine Tex. I've used tha before on feathering in edges from nose cones I installed on my 242. Don't honestly know if it made much of a difference or not, boat only ran mid sixtys anyway. I'll end up using Marine Tex throughout cause I don't want problems down the road. That's an interesting concept what you did at the transom edge. Think I'll try that as well. Thanks. Russ

The lip works well on a light boat, but I'd be a little concerned about getting it broke off coming on and off the forklift (mine stays in dry stack). You'd also have to make sure your trailer was easy on the trailing edge.

We also used the lip on the inside of the left rear sponsons on tunnel vee circle race boats. Turn so hard your vision would go gray.