kook

Following on the thread of " 2" IMCO shortie"..... It's about time for me to purchase an IMCO SC, and I don't know whether or not to try a more aggressive "X". I haven't gotten much feedback from the factory (Sunsation), as they have not spent much time playing around with the "X" on this boat (25' Aggressor, conventional v-bottom with delta pad) - their bigger selling boats are the 28.8' and the 32'.

The current "X" is about 14". Boat was only running 60mph last season, and this year I'll be at 85...... so, it's unchartered territory. FWIW, I had been running a 24p Bravo1 and needed a good deal of trim to reach best top speed. Chine walk for this hull is known to be in the 81-84 mph range. I will have K-planes this season.

I was either going to stay with the current "X", or buy a 1" shortie IMCO. Would like to hear the (potential) pros and cons, if anyone has a clue. I'll be starting out with a 30p Bravo1.

-Mark

cobra marty

You've changed so much that you don't know where you are now so you don't know where to go. You are going up alot in power and speed so your boat will carry differently than before. Tough guestion. If you get a 2" shorter you can fit it with a 2" spacer to see how it is at that setting and then take it out and see again. If the 2" shortie is not it, at least you will have something that someone will buy. Who wants to buy a std. length lower if you don't like it and want to sell it. And who is to say a rh 30" prop is it, maybe a lh 30" would do better on a single? As usual happy testing.

Tinkerer

Like cobra marty said beter too high than too low. You can add spacers to bring it down if needed. Is the drive mounted so that the cavitation plate just above the propeler is even with the pad of the hull when the drive is paralell to the bottom of the boat? If it is than a shorter drive will probably help or even if it is up to 1 1/2 inches higher than the pad. You will have to run a 4 blade prop with a lot of cup like a BRAVO Prop.

Cord

iTrader: (2)

I third cobra.

Brad Perry

I'm assuming that the mentioned 14" is the distance from the pad to the crankshaft centerline. That sounds conservative to me. Mine is 15.5" from the factory ona pad bottom, and I have no negative issues, and was told by the designer that it could be raised an inch or so with good results. I would always rather have a short drive that can be shimmed rather than the other way around.

kook

I assume only the spacer and vertical shaft are what's needed to increase the length?

mcollinstn

the spacers I've seen have a splined insert in them. Does this mean that you run the same vertical shaft with and without the spacer? Does somebody know the answer?

26scarab

Kook,
Talk to Lee on this board , he has raced alot of Sunsations and knows quite a bit on the set up of them.
My experience with friends that have had Aggressors is that they carry the bow very well so adding the shortie shouldn't hurt even though you will be losing some leverage.
I hope you have external steering and some BIG k-planes !
85 in an Aggressor You the MAN !!

cobra marty

The spacer is easy - spacer, longer studs, and a longer coupler that goes on top of a std vertical shaft. Easy on and off if it doesn't work.

Maxx

Kook, I am dealing with the same issue. I swapped from an Alpha1 / small block to a Bravo1 / big block. I ended with an X dimension that's a little over 2" too low. I opted to cut the lower rather than move everything else up. If you decide to go with the Imco shorty, keep me posted I would be interested in your results. As it stands now, I have the lower disassembled and will be mounting it in a vertcal mill to cut it down.