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View Full Version : CLE VS. SPORTMASTER WHICH IS FASTER? AND WHY



2.5-21
05-14-2001, 08:28 PM
WHICH GEARCASE IS FASTER? IF YOU HAVE THEM ON THE SAME SETUP AND THE GEARCASE IS NEAR SURFACING I NEAD TECHNICAL REASONS NOT JUST SOMEONE SAYING THEY TRIED IT

WillyT
05-15-2001, 08:32 AM
Here is my best shot at answering your quesiton. As I understand it, the CLE is really only "bad" on rigs requiring positive trim to run at their best, and/or rigs that require the gear case to be well down into the water to help carry the bow (i.e., on most "pleasure boats"). In a "parallel with the water" and in a "surfacing condition" (i.e., on real light/fast high performance boats that do best in this configuration), I think it does well. The Sportmaster is longer, and while "common sense" may tell us that a bigger gear case should be slower due to more surface area drag, fluid dynamics does not always follow common sense. The longer case apparently lets the water "follow" the surface better (less turbulant flow, less voids/bubbles, more "solid" flow to the prop etc.; I guess you want laminar flow not turbulent flow) and also lets the water "release" better at the trailing edge. Net result is less overall drag and better water into the prop. The deeper you run your case, the more these things can come into play, hence the more the Sportmaster helps. Run high and straight, I don't think that there is much difference. In some cases on real fast/light boats, the CLE MAY even prove to be a little faster. On most high performance "pleasure boats", the Sportmaster seems to due better (for the above reasons). In several tests, however, the Bob's cone has proven to be faster still. When you are talking about complex/curved shapes moving through a fluid, trial and error is sometimes the best way to come up with the best design. If a fluid flow computer calculation could produce the "perfect" design, the outboard engine and aftermarket cone manufacturers would all be making the exact same shaped cones for the same specific end use.

Mark C.
05-15-2001, 01:25 PM
Excellent post, Willy. I've seen a few people post that the Sportmaster is the latest and greatest and therefore the best, period. I've been told by some - and believe me I've talked to quite a few "experts" on this - that the Sportmaster has its own set of problems, sometimes requiring some grinding and shaping to run well. The key to your response is that you just can't make a generic statement that one is the best - it really depends on the application. Your description of their characteristics matches what I have learned. Nice job!

bill mason
05-15-2001, 05:09 PM
I have run both on my new allison and the sportsmaster is five miles and hour (gps) than the cle with a Bob's nose cone and torque tab. The cle will start to blow out at 90 but can run the sportsmaster full trim 1 1/4 above pad 96 gps no problem. Handling lot better with sportsmaster my 2 cents

Frequent Flyer
05-15-2001, 07:53 PM
When making this comparison the skeg plays a major role in performance. For starters I'm going to assume that all cases have the cut back (or slanted back) bone-stock skegs and no nose cones. The new style CLE's and sportmasters have a wider, beefed up skeg while the old style CLE's have the narrowest skeg. So when comparing the new style CLE to the old style CLE, the old style hands down is faster. Now the old style CLE vs. the sportmaster is a tough one since what the sportmaster loses by its skeg width, it makes up for by its lower water intakes which allows for even higher enginer heights (that's if you like running with water pressure). So for tunnel hulls that like extra high engine heights this is a major factor. However, for V-bottoms where the propshaft centerline is lower than the pad (ie; allison), the sportmaster will slice through better by its length. So in that case it would be fair to test the sportmaster against an old style CLE with say a JC's or Bob's nosecone to bring the lengths equal and compare the skegs. This also explains why the sportmaster skegs are modified by thinning and shaping.
Hope this helps,