Maxx

Tomcat, I appreciate your input on the testing. However, my purpose for testing, at this point; is durability and Tom's boat fits that bill perfectly. I believe that most performance boaters are aware of the pros and cons of a raised X dimension as proven by the popularity of the Imco units. My goal is to provide a less expensive and durable alternative. As you have mentioned, hull design and stock X dimension will be a factor in whether someone should consider a 1 or 2" shorter lower. I plan to perform a detailed performance test on my boat (1989 Chaparral 2350sx) at a later date, but bear in mind that the gains I may see could be totally different from another boat with a more aggressive hull design. I will post all of the performance results and thanks for the encouragement.

Shawn, I was able to compensate for the water intake issue.

tommy v

HEY TOM CAT FIRST OF ALL TEST WILL BE CONDUCTED WITH A 3 BLADE MIRAGE PLUS THE PROP YOU SEEN ON THE BOAT WAS A TEAST PROP THATS WHY IT IS BLUE INCASE YOU DID NOT KNOW I HAVE A GPS SPEEDO GAFFRIG AND WILL POST ACCURATE BEFORE AND AFTER INFO IM SORRY IF YOU ARE NOT HAPPY WITH THE TEST BOAT BUT IT IS NOT YOUR CALL I WILL TELL YOU BOAT WEIGHT ALL SPECS WILL BE AN HONEST TEST NOT EVERYONE HAS LITE WEIGHT HIGH HP BOATS ..THE RESON I HAVE THIS PROBLEM IS FROM LISTENING TO PEOPLE ON OSO WHO GAVE ME THE WRONG INFO THTS WHY AM SO DEEP AN ALPHA SS DRIVE IS 2''SHORTER THEN A STOCK ALPHA AND A BRAVO IS A 13/4 LONGER THEN A STOCK ALPHA WHICH MAKES IT 3 1/2 TO DEEP I KNOW I HAVE TO RAISE MY X DIMENSION AFTER TALKING TO MAXX HE AGREED TO HELP ... IF HE CHOSES TO RE TEST WITH SOMEONE ELSE THEN HE CAN DO SO TOM

tommy v

TOMCAT THE PROP SHAFT FROM BOTTOM OF KEEL TO CENTER OF PROP SHAFT IS KNOW 10'' WITH THE SHORTY THAT I AM TRYING WILL BE 8'' BEFORE I DID THE CONVERSION FROM AN ALPHA TO A BRAVO WAS 6'' BOAT WEIGHT IS 5600 LB ANY MORE QUESTIONS

tomcat

Maxx

Reliability is the most important thing. I just assumed the test was aimed at demonstrating a speed increase. Again, good luck.

tommy v

You need to relax a little. OSO is all about good (and sometimes bad) advice freely given in an open forum. My post was not an personal attack on you or your boat. I'm just trying to help, so take it easy.

cobra marty

WOW 10" bolow the keel. I've heard that problem with going from alpha to bravo and t prop ends up 4" lower if you just bolt on the gimble to the alpha location. Otherwise it requires glass work and raising the engine. IMCO was able to cut a bravo lower 3" shorter at one time. Your boat sounds ideal for durability/strength testing.

Budman

Can anyone else verify that the Bravo's are longer than the Alpha's? I also did the alpha-to-bravo conversion, and am not seeing the speed numbers that I expected. I was always told that they had the same distance between input and prop shafts.

Brad Perry

"IM SORRY IF YOU ARE NOT HAPPY WITH THE TEST BOAT BUT IT IS NOT YOUR CALL " EEK! Him mad!!

Maxx

Budman, I measured the two when I did the conversion and they where about the same distance between the two shafts. I believe the problem is that the Bravo just has a much larger lower. Thus, more mass more drag. BTW, cool dog!

Budman

Maxx,

Thanks, that makes me feel a little better about my swap. I was starting to think I was going to need one of you shorties. Still might - still not getting the kind of speed that I should. It is a 1.32 ratio with a nose cone - we are going to experiment with a 1.5 ratio in a week or two to see if that makes any difference. Gear ratios/prop selection has been discussed at length on this board before, so why not throw some more fuel on the fire?

That is my dog Buddy, at a pre-cruise party in Evansville, In. He also answers to "Budman", hence my username. I adopted him from the nearby humane society when he was about six months old. We think he is a lab/golden retriever mix, with maybe something else thrown in for good measure. He is a great dog - loves the boat. He is very happy in that picture because he just got leighed - twice!

Maxx

Budman, that's what got me started on this whole project. I contacted my boat manufacturer and they informed that they move the X up 2" for Bravo / big block installations on the same model boat. I definitely agree on the 1.5 ratio, and you may want to consider removing the nose cone. I am going to try mine without a cone first and then install one with a minimal amount of epoxy and try it; then if the nose-cone is a detriment I can knock if off with a little heat.

That is my dog Maxx, hence mine name too, he's a full blood Chesapeake Bay Retriever ( we think, no papers ). Anyway, he stopped a neighbor's toddler from falling in the river one time, so I thought it would be kind of cool to put his picture up somewhere.