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Post by nala on Feb 22, 2017 21:11:42 GMT -1
This is what will be pushing my Hydroforce Mirovia 3.3mtr air floor sib ... there are a few youtube vid's of these boats !!! But won't be taking it out on a trial run for a couple of months.........
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Post by philpot on Feb 23, 2017 11:34:08 GMT -1
Cracking engine Alan, I take it that it is a 4 stroke, the two strokes are a legend with sibs but any Tohatsu is top notch.
Phil
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Post by nala on Feb 25, 2017 18:18:32 GMT -1
Hi Phil , It's a 2stroke and im itching to test it out.....I've watched so much youtube vid's on the engine and my sib the Hydroforce mirovia 3.3mtr which makes me feel confident with the purchase's. Ran it in a water tub so hoping to get it on the water by the end of March ? I need to set up the sib with all the kit on it so it'll be an all or nothing moment. And time the battery charge, to power the Lowrance dsi4 fishfinder /sonar/gps and it's running time it's a Clulite battery........ I'm hoping i'll get about 6 to 7hrs. Was sad to see the Parsun go, but on a positive side I've got some extra space in the garage now ! Tight Lines
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Post by davidbennett on Feb 27, 2017 13:26:15 GMT -1
Just bought lovely 10hp of gumtree for £250 Too good to be true at the mo: It purrs in neutral, clunks into forward and reverse Waters pouring out Engine sounds nice in high revs Very clean inside Bought from an ex engineer who serviced it himself once a year I ve got an 3.8 v shaped air floor sib Presume this will easily plane with one but what about 2 people?
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Post by davidbennett on Feb 27, 2017 15:29:33 GMT -1
Its a 2 stroke btw
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Post by philpot on Mar 5, 2017 22:44:57 GMT -1
It will plane fine David but with that size/weight of boat, two up, you may find you are running higher revs to keep it on the plane and perhaps a bit more effort getting up there. Get you friend to be right up at the bow to assist getting the boat on the plane.
If you have issues, let me know as I may have two 15hp outboards for sale very soon.
Phil
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Post by davidbennett on Mar 6, 2017 12:59:16 GMT -1
great thanks for your advice itchin to get on the water!
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Post by davidbennett on Mar 28, 2017 16:00:28 GMT -1
had mine out today feels like so much more power than a 6hp and I love it! gets on the plane in seconds now but after about 5 secs its sounds like the prop is coming out of the water as the noise of the engine is louder - caviatation? what can I do ? Cheers Dave
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Post by davidbennett on Mar 29, 2017 9:25:46 GMT -1
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Post by philpot on Mar 29, 2017 13:21:23 GMT -1
Right David, this can be a minefield so one step at a time matey. One big issue with an air floor is the lack of rigidity that you have with an aluminium floor and to a degree a wooden floor. This lack of rigidity causes the floor to move quite a bit under power and the water passing under the boat can cause a 'mexican wave' going on under your feet with the floor raising and then the wave motion running back under the boat length.It is also worth noting that you do not just have water running under the boat but air as well caused by the boats motion which in turn makes things worse. It would be helpful to know what make/model of boat you have and if you have a flat air floor or a 'V' air floor and if the floor can be removed. There are several things to look at and at this point, we cannot say if the issue is cavitation or ventilation. The floor pressure is critical on an air floor and MUST be kept at the stated pressure, usually around .7 - .8bar. Once the boat is on the water, the pressure may well drop down because of the water temperature. Now it is likely that you would not notice any problems with a small outboard because you were not reaching higher planing speeds. After the boat has been sitting on the water for about 15mins, check the pressure and pump up if needed. If you are pumping by hand / foot pump, you will need a manometer to check pressures. If you don't have one, you can get one from ebay. EVERYBODY who has an inflatable boat should have one............. www.ebay.co.uk/itm/Inflatable-boat-dinghy-air-pressure-gauge-manometer-fit-halkey-roberts-honwave-/142321304827?hash=item212302c4fb:g:KvgAAOSw4DJYih~USo that is the first thing to check and in many cases it will be the fault. In some cases where the air floor is removable, a piece of wood can be slotted under the air floor near to the rear of the hull to offer a certain rigidity at the area where the engine is so the water will to a point become more of a even flow under the hull allowing the engine to work with out ventilation or cavitation having any effect. The wood could for example be 12'' deep by the width of the floor or possibly in two halves to fit a 'V' floor that is of course if the air floor is removable. However, there are other things that may be to blame. engine height on the transom. Quite often the transom can be very shallow causing the engine to sit too low. Link this to the water flow under the boat and you have a ventilation issue. A quick and easy way to establish if this is a problem is to cut some pieces of wood to the thickness of your transom ie. 30mm and about 10'' long by perhaps 5mm thick. If you make a few of these, say 6, that will give you an increase in engine height of 30mm max. To test the best height for your engine (once you KNOW the floor pressure), do a test run with one piece of wood under the engine clamp which will lift the engine by 5mm, no good ?, okay now use insulating tape to fasten two pieces of wood together and place under the engine clamp and repeat the test, and so on until you have reached a suitable engine height. It may be that the height you need to reach is higher than the engine can be clamped because of the engine bracket is no longer clamping against the solid wood of the transom, in which case the transom needs to be built up and before we get to that stage I am going to need to see so photo's of the engine in situ on the boat showing the height needed then I can have a word with my local marine engineer in the next village to see what he suggests. It is quite often the case that the transom height is built up and then faced both sides with thick aluminium sheet to offer a strong transom as that is going to be needed when you consider the the torque from the engine. It is possible to look at the propeller size and pitch but to be honest that is something I have VERY little knowledge on so an marine engineer is needed to look and make an assessment on what to try and some of them will have s/h or a loan prop which you could test, then order a new one but that can be looked at a later date. If some of that needs explaining a bit more, please let me know. It is always tricky to be able to get across information that makes good sense to me because I have seen it or worked on it but to somebody else who is not familiar with the subject..........................well you know what I am saying. Phil
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Post by davidbennett on Mar 29, 2017 14:28:09 GMT -1
omg what a minefield! think I better get testing - just a series of trial and error I suppose I let you know how I get on Thanks for your amazing knowledge!!
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Post by philpot on Mar 29, 2017 15:01:40 GMT -1
PM inbound David
Phil
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