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Old 30 August 2014, 05:41   #31
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Having the same problem myself. Solo it runs great, add passenger and I have to get creative on weight placement. Even a difference of 10# of the passenger make it a whole new situation. I am running at 5000' above sea level so I do need a lower prop pith to adjust to this hieght. I suspect an under inflated keel as the tubes and floor feel hard when correct on pressure settings. However, the keel still feels soft when even above the recommended specs. How much over pressure specs will these thing take?
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Old 17 September 2014, 06:12   #32
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Just returned from holiday and preparing for some tests to address this issue. Listing the tests, I have the following
1 try the boat at speed solo to see if there is any difference.

2 check pressures and again after leaving it on the water for about 20 mins

3 take a couple of wood shims at 1 cm thick to see if the height improves things both solo and with a passanger

4 try a piece of 6mm ply full width of the floor and about 12 - 18'' towads the bow. This is to be placed below the air floor.

5 mark the prob and hub/shaft to check for spun hub

6 try different trim positions when I am happy with the pressures

7 take a stove to keep me going with loads of coffee me thinks

Now is there anything else I have over looked guys and I will add it to the list.

I would like to say thank you to you all for your input so far.

Phil
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Old 17 September 2014, 09:00   #33
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If it's driving you mad Phil I hope you find a solution with your outfit. However my experience with air floor sibs (the flat type like yours not the V Aerotec type) is that the slightest thing can trip them into cavitation/ventilation/prop slip (whatever you would call it). A certain combination of boat make, load weight/distribution, outboard make and even prop type/condition can cause it to be an issue... then even if you find a perfect setup certain sea states can induce it.

So for me I accept it as a possible/occasional part of the air floor character offset by their great portability and ease of inflation.
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Old 17 September 2014, 11:39   #34
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I had an aluminium floored Seapro 340hd and also suffered with cavitation issues. So perhaps the floor/boat type isn't particularly the issue. Funnily enough I was using a Parsun 15 like yourself. Perhaps it's the engine? The only thing I found helpful was to trim it right in as close to the transom as it would go. This improved matters re the cavitation but I was left fighting with the tiller as it seemed to then be greatly affected by the torque from the prop. I did find the Parsun 15 to be quite a heavy motor for that size of boat.
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Old 17 September 2014, 11:46   #35
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Now is there anything else I have over looked guys and I will add it to the list.
8 Try moving the passenger forward and backwards to see what changes.
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Old 17 September 2014, 14:08   #36
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I am inclined to agree with you Fenlander and wish to god I had gone for the aluminium floor but having said all that, I do love the ease of the air floor so a compromise is needed.

The Parsun is a 15hp 2 stroke weighing in at 37 kgs Martin so I would have thought that not to be too heavy and I have bought it now so fingers crossed, having said that I am going to buy a little 2.3 - 4 hp motor for my river/lake fishing which will be a fair percentage of the use, scanning ebay as we speak.

I forgot to put that on the list Peter so as I cannot edit the list on here, so a note has been made to test that out.

Phil
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Old 17 September 2014, 14:54   #37
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Mine was a 4 stroke Phil and much heavier than that so just ignore me !! Hope you get it sorted
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Old 23 September 2014, 15:28   #38
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Well I have been playing on the sib today trying various things to improve the cavitation / ventilation issues. I set the pressures and checked them with a separate gauge. After launching, I moored up on the river, had lunch and fished for a little while, actually 1 hour. Pressure test--------------fine so on with the test run.

No signs of the cavitation whatsoever, same with two on board so pressure was to blame I guess BUT wait for it, we now have a Mexican wave going on under the floor. Difficult to really describe but the water or air is passing under the floor with a steady movement lifting the floor by what seemed a couple of inches as it worked it's way under the hull.

This is driving me MMMMMAD

Phil
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Old 23 September 2014, 15:47   #39
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No signs of the cavitation whatsoever, same with two on board so pressure was to blame I guess BUT wait for it, we now have a Mexican wave going on under the floor. Difficult to really describe but the water or air is passing under the floor with a steady movement lifting the floor by what seemed a couple of inches as it worked it's way under the hull.

This is driving me MMMMMAD

Phil
that phenomenon has been described here by others in the past...
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Old 23 September 2014, 16:03   #40
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Yes indeed... only last night, having just bought an air floor Zodiac we hope to get on the water this Sunday, self and Mrs were pondering if it would have the air floor character... as if you passed over the back of a whale now and again.

Part of the experience!
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