I need help finding the right props for a twin outboard v hull.......
04-03-2013, 11:58 AM
#11
coolrunning racing
VIP Member
I did not like it when we set out boat up turning the in. This creates transom lift and by piling up the water between the props it will effect the stability. So I turn mine out, more consistent handling characteristic. The center of gravity is going to be a big factor as well. You can not correct a bad set up with just props.
04-03-2013, 01:35 PM
#12
Offshoreonly Advertiser
Offshoreonly Advertiser
I did not like it when we set out boat up turning the in. This creates transom lift and by piling up the water between the props it will effect the stability. So I turn mine out, more consistent handling characteristic. The center of gravity is going to be a big factor as well. You can not correct a bad set up with just props.
A lot of people don't like this because the boat can because feel loose or flighty.
Brett
__________________
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
Brett Anderson / BBLADES Professional Propellers
920-295-4435 http://www.bblades.com/
[email protected]
04-03-2013, 09:38 PM
#13
Registered
Thread Starter
its so hard to find the right info.....but i agree with mrv8outboard....turning in feels less predictable....but as i understand, turning in is usually faster.
i dont mind the boat running loose....id like the boat to fly flatter in the rough and ride with the bow lower....i spoke to some guys that used to race the 2800 checkmate and they said when the boat was set up correctly , it required almost no positive trim at WOT. i have to trim to get the boat to loosen up and run fast.....but i did notice that when i raised my engines up last year it required less trim to run max speed and less trim to get on plain.....
Brett....
is it true that burying the props deeper (lower x dimension) leverages the transom more and gives more bow lift and running the prop shafts more shallow (higher x dimension) gives less leverage and therefore less bow lift????
i noticed that last year , rotating props in, when i raised the engines from dead even to 1.5 inches above the hull in front of the bullets....it helped the boats speed, acceleration, and porpoising alot....
i am now at 2" above the hull courtesy of moving the engines closer together.
04-04-2013, 03:46 AM
#14
Registered
throw out typically and usually. This will drive you crazy. Every change to pitch, rake, diameter, no of blades, blade design, trim settings, drive height can have different trade offs in different boats.
You need a good baseline. You need to know if the boat needs more bow lift or less...more transom lift or less. maybe more bow lift AND transom lift....maybe a combination.
If you want to get the boat propped correctly listen to Brett. Then try as many props as you can with his test program. always test with the same conditions.
You need a good baseline. You need to know if the boat needs more bow lift or less...more transom lift or less. maybe more bow lift AND transom lift....maybe a combination.
If you want to get the boat propped correctly listen to Brett. Then try as many props as you can with his test program. always test with the same conditions.
04-04-2013, 04:03 AM
#15
Registered
can anyone give info about getting the props right for a 28 foot v hull that has alot of setback / natural bowllift????
ive been running merc chopper IIs but that is a bow lifting prop, the 2800sx is a "pad" bottom boat and it has a heavy transom due to the 30 inch setback with twins on it so i dont know if i really need a bow lifting prop......
seems like a prop with a little less bow lift and more stern lift would help the boat stay on the pad......
small ear chopper????? cleaver?????? Merc et / hoss style chopper??????
ive got ALOT of conflicting answers to this question.....anyone got an opinion????
in a 28 foot long pad boat....with a TON of natural bow lift.....should i be trying to lift the bow even more??? the boat is very light in the bow even at speed.....
the boat has a tendency to porpoise, this can be controlled with the tabs but tabbing down scrubs speed.....the porpoise is because of the boat lifting the bow and not being able to carry it due to improper pad balance / "falling of the pad" at least thats what ive been told.
as i understand it...with a pad boat....its a balancing act (in this instance in the sense of fore and aft....) the boat is riding too far on the aft portion of the pad IMO....
i have also been told that the deeper your props are (x dimension) the more bow lift the choppers create.....and the more shallow they are = less bow lift.....is that true????
the props were turning IN....and as i understand it this creates BOW LIFT....correct???
so should i turn the same chopper props out in order to not carry the bow so high??
what i have now is a boat that runs great but is unbalanced but is managable with the K-planes........i believe due to the style, height, or direction of the prop rotation......
ive been running merc chopper IIs but that is a bow lifting prop, the 2800sx is a "pad" bottom boat and it has a heavy transom due to the 30 inch setback with twins on it so i dont know if i really need a bow lifting prop......
seems like a prop with a little less bow lift and more stern lift would help the boat stay on the pad......
small ear chopper????? cleaver?????? Merc et / hoss style chopper??????
ive got ALOT of conflicting answers to this question.....anyone got an opinion????
in a 28 foot long pad boat....with a TON of natural bow lift.....should i be trying to lift the bow even more??? the boat is very light in the bow even at speed.....
the boat has a tendency to porpoise, this can be controlled with the tabs but tabbing down scrubs speed.....the porpoise is because of the boat lifting the bow and not being able to carry it due to improper pad balance / "falling of the pad" at least thats what ive been told.
as i understand it...with a pad boat....its a balancing act (in this instance in the sense of fore and aft....) the boat is riding too far on the aft portion of the pad IMO....
i have also been told that the deeper your props are (x dimension) the more bow lift the choppers create.....and the more shallow they are = less bow lift.....is that true????
the props were turning IN....and as i understand it this creates BOW LIFT....correct???
so should i turn the same chopper props out in order to not carry the bow so high??
what i have now is a boat that runs great but is unbalanced but is managable with the K-planes........i believe due to the style, height, or direction of the prop rotation......
04-04-2013, 09:07 AM
#16
Registered
Thread Starter
thanks for the input man!
when i tuck the engines the boat slows down but does not porpoise......but as i said in an earlier post.....initially the boat had the prop shafts even with the bottom of the hull.....and i had to trim waaaay up to get the boat run fast and build rpm (porpoise was really bad at this point, even on flat water)......i then raised the engines 1.5 inches and this helped alot....but didnt totally cure the problem: the boat required less positive trim to run fast and build rpm and all around handling improved. it would still porpoise, although only when it got rough and the boat was trimmed up.... but was controllable with the tabs.
i have been told that this hull, when set up correctly....should require almost no positive trim in order run fast and fly flat....partially due to the pad on the bottom of the boat that runs the length of the hull....
i am now at 2" above the bottom of the boat and the engines are 18 inches apart instead of 22.5.....
i am going to be testing my pair of 26 merc choppers and a set of 26 hydromotive intimidators hopefully sometime this weekend.
when i tuck the engines the boat slows down but does not porpoise......but as i said in an earlier post.....initially the boat had the prop shafts even with the bottom of the hull.....and i had to trim waaaay up to get the boat run fast and build rpm (porpoise was really bad at this point, even on flat water)......i then raised the engines 1.5 inches and this helped alot....but didnt totally cure the problem: the boat required less positive trim to run fast and build rpm and all around handling improved. it would still porpoise, although only when it got rough and the boat was trimmed up.... but was controllable with the tabs.
i have been told that this hull, when set up correctly....should require almost no positive trim in order run fast and fly flat....partially due to the pad on the bottom of the boat that runs the length of the hull....
i am now at 2" above the bottom of the boat and the engines are 18 inches apart instead of 22.5.....
i am going to be testing my pair of 26 merc choppers and a set of 26 hydromotive intimidators hopefully sometime this weekend.
Last edited by 2tonchevy; 04-04-2013 at 09:11 AM.
