Posted 29 March 2006 - 10:26 AM
seaslide claims it reduces friction between the hull and water - so i guess a silicon based polish will do the same - it feels slippery! - have to wait and see.
Posted 29 March 2006 - 02:33 PM
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Posted 10 April 2006 - 04:23 AM
after polishing my hull with auto-glym and buffing it several times - managed about 67mph at weekend in less than ideal conditions - 2 persons on board and full tank of fuel
so i will add a few more coats of polish
Posted 10 April 2006 - 05:09 AM
Posted 10 April 2006 - 06:34 AM
Posted 10 April 2006 - 06:37 AM
Posted 10 April 2006 - 06:39 AM
Posted 10 April 2006 - 01:18 PM
I'm going to true my rideplate by filling in the holes and smoothing out the gaps between hull and rideplate...should be good for small increase in mph. I'm also waiting for a new trim tab from BRP, in prototype stages right now. The planing time on this c180 is horrible not to mention porpoising.
I'm going to have this thing flying by this summer if it kills me
Posted 11 April 2006 - 03:32 AM
Posted 11 April 2006 - 10:21 AM
What was your top speed before the polish job?
Posted 11 April 2006 - 11:09 AM
Posted 19 April 2006 - 02:28 PM
Wow.....67 on GPS. Most impressive. I suspect you'll be wearing your arm out polishing that thing though seeings how that polish will wear off rather quickly. Especially if you're boating in salt water which has more mineral content.
Probably the easiest way to increase speed is by decreasing the wetted area and/or breaking the adhesion that occurs when water is passed over the surface of a hull. That's why you see high peformance boats having so-called stepped hulls and notched transoms. The "steps" in the hull create turbulence which translates into tiny air bubbles that break the adhesion resulting in the hull running "free'er". IMHO coatings are mostly snake oil. I've been to many types of boat races from Offshore to Hydro's and have never seen anyone applying some miracle slipery stuff to a hull. What they will do is blueprint the bottom (making sure the hull is symetrical and the bottom contours are consistent laterally and longitudinally) and polish the surface of the hull. As for wetted area, the rule used to be 1" of wetted surface (measured from transom going forward) for every foot of length. IOW, if you have an 18' boat, only 18" of the hull should be touching the water for max speed.
What I think Thumper has done with all his buffing is to smooth out the imperfections in the fiberglass surface. So in essence, it's the smoothness of the hull and not the stuff he used that's rresponsible for the speed increase. When you have thousands of pits and nicks and whatever in your hull, you're adding drag.
That's all for today's lesson. Class dismissed. LMAO
Posted 20 April 2006 - 03:53 AM
Posted 20 April 2006 - 04:06 AM
i will also look to polish my head just to squeeze out a couple more knots
high speed - low drag haircuts are a amjor factor i am sure
watch out for our next photo shoot - when my buddy comes next we are doing an underwater video of start up and drive by to see the pump in action - we are both divers and decided to do this in 6-20ft of water, and also in 3ft of water to see if the pump really does pick up sand etc from the bottom at this depth -
Posted 20 April 2006 - 11:46 AM
I still contend that what you did with the polishing was to increase the suface finish of the hull thereby reducing drag. IOW, you made the surface "shiny'er" just like polishing metal. Normal aluminum (sorry - that's al-you-min-ee-um to you )sheet is rather shiny from the mill yet will corrode quite easily. However, if polished to a very high state, it can withstand corrosion without any coating. Technically, surface finish is expressed in RMS terms - the larger the number, the high the surface finish.
As for stepped or ventilated hulls......there's two camps - those who feel they're the way to go and are safe and those who feel the handling can be dangerous and that other hull designs are more forgiving and have just as good turn of speed.
Steve Stepp and Reggie Fountain both have a very long and very successful history of racing in outboards, formula, hydros, offshore, etc. Steve feels that vetilated hulls, when driven close to the limits, are ill handling and not for the average boater. In the hands of a pro they're fine, but they still have a propensity for spinning out or rolling over in turns that are not executed properly. Steve contends that his pad keel design is just as fast but without the evils of the ventilated hull.
Now Reggie, who all but invented the ventilated hull, feels ventilated hulls are safe in the hands of any boater and that the ventilated hull achieves it's speed more efficiently. Reggie (as well as Steve), has set many UIM records so the numbers should speak for themselves. However, numbers don't tell anything about a boat's handling when running - especially flat out. I'd love to be in a room with these two guys debating the subject. It would be most informative and entertaining.
As for how a ventilated hull would affect the intake of a jet pump - i.e lead to cavitation issues.....I suspect there wouldn't be any issues. The steps are typically well outboard of the hull's centerline and are the most prominent at the hull's chine. Since the hull is displacing the water (even when on plane), the flow of water off the hull is outward as witnessed by a boats' wake. It's possible that SeaDoo knows about the handling ills of ventilated hulls and just don't want to deal with the potential liability issues.
In next weeks lesson we'll cover chine walk and how it leads to boat seat butt suction.
Posted 21 April 2006 - 04:14 AM
i would ask if you could explain some of your abbreviations - they are a little puzzling!
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