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Old 01 January 2022, 11:37   #21
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Hi I do pump it to correct pressure although I’ve not checked after in the water and is it important t to inflate in correct order ?
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Old 01 January 2022, 11:55   #22
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The engine is brand new and swapped props to eliminate that, the boat can be fine and planes well then all of a sudden the prop loses grip and you need to drop the revs and go again ?
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Old 01 January 2022, 12:01   #23
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So just the possibility you might need a bit more air after it's settled on the water but if that, weight distribution, OB trim and a prop change hasn't sorted it you may just have an outfit combination that is prone to this... some flat air floor models are are.

One more thought though... where is the outboard AV plate height related to the bottom of the transom?
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Old 01 January 2022, 12:10   #24
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It’s a little lower than should be, some people say the Suzuki 6 is 50mm too long but I did raise it and no massive difference, the best change when on my own was sitting more up front, this post was made my someone with the same set up so I’ve messaged him, need to double check pressures as I’ve not checked that as using the air pump that you pre set for each tube and floor pressure so it should be correct, but maybe I need to check when it’s been sitting on the water for 10 mins, is it that critical ?
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Old 01 January 2022, 12:20   #25
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My pump was indicating correct pressure last year got on the water same trouble as you with floor flex tested with another pump to find pressure well out just a thought. My excel cavitates when the AV plate is level with the keel first boat I’ve owned that does this.
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Old 01 January 2022, 13:15   #26
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Thanks for the tips will set up and test pressure to see, thanks Rich
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Old 01 January 2022, 19:14   #27
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As previously stated by Jeff and Fenlander, pressure, pressure and again pressure. Deck pressure and keel pressure pumped to max, then 15 mins after being in cold water checked and pumped up again. An hour later I check and adjust the pressure.
I think you will find that the Excel has bigger rear tube cones that make the stern sit higher in the water. I found that sitting the OB on the transom (no packing), pressure exact for deck and keel, and trimming well (at least 50kg incl fuel) up front, help to reduce slip.
I have only experienced what I would consider prop slip a couple of times and that was down to the keel and deck being under pressure.
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Old 01 January 2022, 19:36   #28
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Thanks, so the pressure must be that important to these boats, one quick one then you know when you get to the correct pressure when you remove the pump fitting there is a little loss of air, would you pump just a tiny bit over to allow for that ?
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Old 01 January 2022, 19:46   #29
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I don’t bother it’s minute
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Old 02 January 2022, 10:56   #30
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Sorry to hijack the thread.
Can someone explain what prop slip is please.
On my outfit, when I open up to get on the plane sometimes I get what I can only describe as a jolt or as if the engine has missed. It only does it now and again and only when opening up
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Old 02 January 2022, 11:00   #31
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Sorry to hijack the thread.
Can someone explain what prop slip is please.
On my outfit, when I open up to get on the plane sometimes I get what I can only describe as a jolt or as if the engine has missed. It only does it now and again and only when opening up
You can get slip in aerated water or in certain wave heights etc or if your engine is a bit high. If it only happens now and then just leave alone it might be weight distribution too
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Old 02 January 2022, 11:06   #32
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You can get slip in aerated water or in certain wave heights etc or if your engine is a bit high. If it only happens now and then just leave alone it might be weight distribution too

Does it sound like possible prop slip?
My initial thoughts was temporary fuel starvation from idle to wot and was going to strip the carb
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Old 02 January 2022, 12:01   #33
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Brand new engine so it runs perfectly, just checked pressure gauge and when I’m out next will see how it goes, could have been a little low on pressure 😊
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Old 02 January 2022, 14:21   #34
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Brand new engine so it runs perfectly, just checked pressure gauge and when I’m out next will see how it goes, could have been a little low on pressure 😊
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Old 02 January 2022, 14:24   #35
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Does it sound like possible prop slip?
My initial thoughts was temporary fuel starvation from idle to wot and was going to strip the carb
Are fuel filters clean. Is it a two stroke engine?
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Old 02 January 2022, 14:58   #36
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Are fuel filters clean. Is it a two stroke engine?

Yes 2 stroke Yamaha 5hp. I'm sure it doesn't have a filter from the internal tank line
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Old 02 January 2022, 15:47   #37
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Yes 2 stroke Yamaha 5hp. I'm sure it doesn't have a filter from the internal tank line
It might be in the tank outlet it is on my 3.5 Mercury, two strokes do blip sometimes in my experience I wouldn’t worry
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Old 02 January 2022, 22:27   #38
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Hi Tommy, before you go stripping down your carb, I'd consider checking if your av plate is to high, boat trim, weight distribution, one up/two up, opening up when not straight, deck/keel pressure?
If your ob runs well under normal circumstances, why do you think it could be fuel starvation when you open her up? and if it doesn't happen often, does it matter?
My prop slips, not often. But it slips, if I open her up in choppy water, if I open her up at the end of a turn, if I open her up when to much weight is initially forward.
If you think about it, nothing about water, a flexible boat and a variable speed prop lends itself to consistency, so you will inevitably never run an OB to its optimum, just try to get as close as you can.
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Old 03 January 2022, 07:58   #39
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Hi Tommy, before you go stripping down your carb, I'd consider checking if your av plate is to high, boat trim, weight distribution, one up/two up, opening up when not straight, deck/keel pressure?
If your ob runs well under normal circumstances, why do you think it could be fuel starvation when you open her up? and if it doesn't happen often, does it matter?
My prop slips, not often. But it slips, if I open her up in choppy water, if I open her up at the end of a turn, if I open her up when to much weight is initially forward.
If you think about it, nothing about water, a flexible boat and a variable speed prop lends itself to consistency, so you will inevitably never run an OB to its optimum, just try to get as close as you can.
Yeah I'll try it next time shifting weight about and, after reading other threads, that the tube pressure is correct.
The outboard is direct on the transom so it's mounted as low as it can be.
My train of thought re fuel starvation was because it was doing it when going from idle to wot so just thought the fuel supply couldn't keep up temporarily as it's quite a sudden thing.
Someone at the time suggested dog clutch slipping but it only does it once or twice in-between reaching top speed, once on the plane it's fine.
I hadn't heard of prop slip til reading about it here so obviously don't know first hand what it feels like or how to identify it
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