So how would a vee hull and standard bravo drive react to a tube....if it's not set up near the surface? It seems in theory it will still introduce air at the leading edge of the prop causing it to rev higher thus being able to run a higher pitch prop which would create more speed? Or would it just make the slip be unmanagable?
Thread: 2 aerate or not?????
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03-27-2012 08:45 PM
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03-28-2012 07:28 PMI'll see who knows, but my gut feel is that an aeration system on any drive would only work on surface piercing types. They load up when they are fully submerged underwater, and once up and moving they aerate themselves automatically. I cannot imagine a scenario where the submerged style of a Bravo would need any aeration because it is designed to not aerate, ever.
Now, one of the new IMCO Bravo surface drive would be a different story...Getting bad advice is unfortunate, taking bad advice is a Serious matter!!
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03-28-2012 07:47 PM
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03-29-2012 05:48 PM
Plenty of room in there for a small family.
Parabellum FJ²B
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03-29-2012 06:22 PM
Hey Rat, how do ya like that pic ya punk!!!!!
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03-29-2012 10:25 PMIt will let the props free wheel as it trys to come on plane. It is possible they would prevent it from getting on plane. Once on plane props need clean water to work effectively.
Does it labor to get on plane now? If you push the throttles all the way forward while putting it on plane how high will the rpm's go? What props are you running now?
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03-30-2012 08:32 PM
Mine, single engine, gets on plane fine
It will rev to ~3500 rpms during take off.......and that is full power to get it there
Unlabbed 28P B1.
My plan still is to labbed a prop..........but my question was more to how a bravo would act with one. You kind of answered my question when you said the prop needs clean water to perform properly....it probably would let it spin more RPMs but it would have a negative affect? I already have a stelling extension box in middle position..so raised 1"...and an IMCO 2" shortened lower.....so how far below the water is the cavatation plate while on plane? It is 3 1/2" below the bottom.
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03-30-2012 09:50 PMThe cavitation plate should be well clear of any water.
Parallel the prop shaft with the bottom and measure your height. That should be about 3 1/2 incahes below on a 80 mph boat.
Some propellers have the plastic plugs or holes in the prop near the leading edge. They are there to adjust the slip getting on plane. If you have them what ever size hole you have now a little larger will allow the R's to go up thus giving it a better hole shot. Not that it is really that important if it is not laboring now. If it was laboring adjusting the slip could be beneficial. The tubes on a surface speed master type drive are there because in some set ups it will only turn 2500 r's and it bogs and never comes up . The tubes allow it to rev up and get up on plane.
The thing is if the height is up and the set up is good usually it slips too much. If it isn't slipping at all the drive must be pretty low in the water. All the shorties and boxes raised do little when it starts out low. Sometimes the best thing to do is actually raise the cut out and re rig the engine to get the height where it needs to be.
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04-04-2012 01:23 PMSounds like th perfect height. It looks as if you may have the same issue that I possibly have. The thick part of the lower is so close to the water it actually may come in contact as the water rises behind the transom.
Getting bad advice is unfortunate, taking bad advice is a Serious matter!!
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04-04-2012 01:28 PMSurface piercing props are designed totally different from a normal Bravo prop. The surface pierce prop is cavitating all the time because it is leaving the water surface and re-entering the water surface as it rotates. Allows much larger pitch and diameter than a sub-surface prop like the Bravo.
So, I believe, to run a surface peirce prop on a Bravo, it would have to be a totally different design. Then , with the drive raised that high and the totally different design prop with the l;arge diameter and pitch, you may have to run n aerator to get the rpm's up into the range where the boat would come on plane.
I wonder what IMCO says with their new surface pierce drive Bravo design? Has anyone talked with them?
And last, am I all washed up in my thoughts?Getting bad advice is unfortunate, taking bad advice is a Serious matter!!
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04-06-2012 10:02 AMYep, I cannot wait to hear how it performs and the differences in handling. One of the issues Doller had with my boat on the conversion to 3a's from Bravos was they had to set them deeper than they wanted due to the swim platform. A switch to 5's may change that if his BT shows really good improvement.
Getting bad advice is unfortunate, taking bad advice is a Serious matter!!
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