For those wondering how skis sink…..your ski will be more prone to sinking if it has an alloy pole and a scupper/ oneway valve drain… Reason being when your ski is upside down it forms an air pocket in the hull , however if you have a scupper or one way valve the trapped air will vent out and let more water into the hull. And the alloy pole doesnt self-right the ski as well as the stock foam filled pole does……
i guess what i wrote make those mods sound real bad.....but they not really ........ alloy poles are good because they are stronger...sometimes lighter...pretty much a must if your hard on poles scuppers/oneway valves are good because the get the water out fast...you dont need to turn them on or off and dont get air-locks like bilge pumps do... its not often your ski will be in a situation long enough to take on loads of water
thanks knoxie, that is good info to be aware of...I had'nt even considered those things.....also argee the benefits of those mods far outway the sinking issue...already had twin bilge & since fitting a scupper not one drop of water in carb issue - shldve done it years ago
I was thinking about this last night when I was working on my SJ.. A pole saver with elastic spring between the hinge and saver will cause the pole to come towards the hood and most likely start to right the ski.
Its hard to write this without sounding like a douche. For a displaced volume of water there is a centre of buoyancy e.g. like a centre of gravity but for the displaced volume. For an object to float 'upright' the centre of gravity must be above the centre of buoyancy. The distance between these is how buoyant an object is, but the angle of these is also very important as a 'top heavy' vessel is easier to turn over. If the centre of buoyancy is above the centre of gravity the vessel will become unstable (imagine a loaded hull, with a lot of weight on a small angle). If the vessel 'upright' is an upside down jetski (with a stock pole), the pole will float against the pressure of the spring and provide buoyancy (filled with polystyrene – displaced volume – plus weighs very little). Stock poles are probably filled with polystyrene for this reason – so that the centre of buoyancy is high in this position – higher than the centre of gravity causing the ski to become unstable and try to right itself. If you have an alloy pole you loose this additional centre of buoyancy, and to make things worse the pole is hollow (e.g. not the same principals of displaced volume), has a negative buoyancy (sinks to the extended position and acts as a separate weighted centre of gravity), has surface area and provides drag against righting --- effectively acting like a keel in a sailing boat. If you add a bungee (pole saver) to make the pole want to return to the hood, you will reduce the 'keel' effect the pole has. It will have a lower hinged weight (second centre of gravity) and with a bit of luck your upside down hull will still have a centre of buoyancy over the centre of gravity and right itself. I guess it would be easier if I had just said something like 'imagine a sailing boat with a long vertical keel (alloy sunk pole) and a lot of weight on it (engine hanging from the mounts) and then imagine if they folded their keel up'…
Rumble you have way to much time on your hands to be writing storys like that in work time lol. Another problem is we run stronger pole springs which tend to hold the pole higher!
Yeah... I did think about that too. you would need a tighter pole saver which would basically mean there is no point in having a HD pole spring.. I'm in holiday mode.. Just came back from Ruapehu two days at work then I'm off to Queenstown for the week and then Wellington for a couple of days..
I've put one of those swimming pool float tube things down the centre of my alloy pole, and cables through that... it stops anything rattling as well as being a flotational device
tru not a bad idea i guess is that one of those spaghetti things you get from the warehouse? might be the go...
foam? anybody know if the foam in the spray cans at bunnings etc are closed or open (ie. absorb water) cell?? Who's having a bath tonite??
Cool Looks That does it, i'm buying floaties for my handle bars... (would be a good laugh driving down the motorway ! )
