07-08-2010, 01:18 PM #1
2nd Gen GTX Handling and Sponson Question.
I havenít even ridden these 98 GTXLís but I have ridden the same hull with the 85 and 110 HP engines. If I remember right, they were smooth and comfortable in chop, but the controls and ride had an almost disconnected feeling when on plane like the steering was loose or sloppy. I also remember they would spin out suddenly when trying to hang a hard turn like my SLís. I like the smooth ride part, but want better turning. I have been looking at different sponson designs and came up with this. It has the lift section in the front of the block like the OE for quick plane, but adds a paddle like the aftermarket sponsons. I donít want the paddle to be too deep/ long so that handling is too twitchy in rough water or that I loose top end speed from drag.
Both block and paddle are UHMW Polyethylene. The block is 1.5Ē at thickest spot, angled to match hull and keep lifting surface horizontal / paddle perpendicular. The paddle is .5Ē thk. It seems most sponsons bolt the block to the hull and then bolt paddle to the block, but I was thinking about bolting thru the paddle and block perpendicular to the hull with a longer bolt and an angled counterbore in the paddle. I modeled the OE sponson for comparison.
The .63 inch depth is probably inline with the aftermarket novice/ rec settings, but the paddle is further out, so these sponsons are probably more aggressive than the rec setting. It seems like a good place to start and it is easy to cut down if handling is too twitchy.
What do you think about this design? Any comments on the GTX's handling? Think the mounting method will be strong enough? Anybody running aftermarket?
07-08-2010, 01:57 PM #2
That hull handles just fine, IMO, for what it is. The problem I found in running sponsons was a tendancy to try to hook one which was worse in the chop.
They also try to force the nose down which can be countered with trim, if you had it...
I am not sure of the actual design on the '98 but the OE sponsons on our '02 are just about as good a comprimise design as I could hope for. Perhaps, if they are different, a set of those would be a better idea (if they fit, though I think so, since the hulls are very similar).
07-08-2010, 03:09 PM #3
You're right, I don't want to f a good thing up. That is why I am trying to stay close to the originals. The set on my skis took some hits, warped from age, and were a pain to remove because the foam was misaligned. So between that and not spinning out, I want to replace them. According to old magazine reviews, the GTX sponsons were redesigned in '99 for better handling. I haven't been able to find any good pics to see how they changed.
07-08-2010, 04:23 PM #4
Here is a front and rear angle shot of the sponsons on an '02 GTX (carbed, second gen).
07-08-2010, 08:13 PM #5
Thanks for the pics Krunch. It looks like the only difference is the added hook along the outer edge after the step. That looks a lot like what I was trying to reproduce with the paddle. Here are the 98's.
07-08-2010, 08:31 PM #6
So Krunch, you must be able to hang a pretty hard turn without spinning out? Does that hook hang down about 3/4 inch from the step?
07-09-2010, 09:05 AM #7
I think it is deeper than that. I will get a measurement and let you know.
She handles great to have such a flat tail, I must say. Better than our RX but nothing like my XPL, of course.
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