xb21 motor height OT vs XOB
- Thread starter xb03fs
- Start date
aaronmt
Active Member
Our friends have a tournament ski boat and pulling a tight U-turn at 45-50 is a heeluva ride in it.I cant imagine what it be like in a ally with the wife and daughter in it.I will say that's very impressive for the prop to hold.
RedAllison
Well-Known Member
Just so no one reading this thinks such stunts are advisable or endorsed by A-owners.com, they are NOT! "Bat turns" are pure hell on everything. You better be constantly checking your jackplate, transom & engine bolts! You likewise WILL sooner or later snap a skeg! Another possibility is the shearing off of seat bases, which I hope DONT happen while your family is aboard. Certainly the Allison hull itself can withstand such stresses but that doesn't mean the other various components can!
Just because you can doesn't mean you should!
RA
Just because you can doesn't mean you should!
RA
GotMyAlly
Well-Known Member
Queue up some pics of your bat turn if you want to drive that message home. :beer:
deleted my comments. I don't think what I do in the boat has been misinterpreted so if some can misinterpret if should be deleted. With the familiy in the boat great care is taken and its driven like a pontoon, when I am out solo, I assume an Allison should out corner a Triton or Ranger, I was losing ground in the corners having to slow down so much...
My antics learning the characterists of the boat where done solo on an empty lake. I believe it is benificial knowing what can and cannot be done in certain situations...Jacket and kill switch were on, other boat nearby watching. In fact I never think of looking for new numbers without another boater nearby, never run with out a jacket. ANd when pressing to unchartered territoy do it on wider bodies of water.
My antics learning the characterists of the boat where done solo on an empty lake. I believe it is benificial knowing what can and cannot be done in certain situations...Jacket and kill switch were on, other boat nearby watching. In fact I never think of looking for new numbers without another boater nearby, never run with out a jacket. ANd when pressing to unchartered territoy do it on wider bodies of water.
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JWW8
Active Member
It is a 2013 BasSport Pro with 250 Pro XS
GotMyAlly
Well-Known Member
I'd be very careful trying to run that one above the pad. In fact,I bet it is unnecessary to get your best speed. My 08 routinely ran above the pad. 3/8"above to 1/2"above was not uncommon. My13 hull is completely the opposite. When I ran 98 at the rally,I was just below the pad. This one really does not like to run above or even with the pad. Not sure if all the 13s are that way or if mine is an anomaly.
I am of the opinion every boat, how it's loaded and prop are a little different. After a while you know what feels right and what doesn't. Measurements get you in the ballpark no more no less. Different heights require different amounts of trim....so even driving style come into play a bit. See the original reason of the thread the OT drove over an inch higher than the xOB before losing pressure and bite. FYI with my 200 the xOB limit was water pressure with the OT it lost bite and set down...it let loose with out the tell tale right lean the 2003 had which is the main reason for selling the prop besides lack of midrange on the 21 boat it had on the 2003. Leading me to believe the xOB is a safer prop on a 21. Granted it
Set down and stayed straight that was probably only due to me having the lighter 2.5 with the only 200hp at only 81 mph
Set down and stayed straight that was probably only due to me having the lighter 2.5 with the only 200hp at only 81 mph
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JWolff
Active Member
To ensure I am getting the right heights on my motor, do you measure to the lowest point on the boat, i.e. the lowest point of the lip, or do you measure just in front of the lip a few inches? Seeing guys talking about 1/2"-1" above pad sounds like measuring to the lip because my jackplate all the way up looked like I was in the 3/8" above the pad range. My motor is mounted as high as it will go from what I can tell on the motor mounts. So I don't understand how one can be 1" above the pad.
The guy I bought it from said the jackplate gauge should be around 3 o'clock. I will have to measure what that is when I get home but off of memory that seems way under the pad, like an 1" or more.
Thanks, John
The guy I bought it from said the jackplate gauge should be around 3 o'clock. I will have to measure what that is when I get home but off of memory that seems way under the pad, like an 1" or more.
Thanks, John
GotMyAlly
Well-Known Member
I always measure just in front of the lip.
As they come from the factory with the 5.5" hydraulic and small spacer plate, using the middle set of holes set the propshaft about 1/4" below the pad when the jackplate is topped out. If you move to the 4th bolt hole, all the way up is about 1/2" above. That's been my experience with two 21's and 3 different motors. I haven't had the need to run on the last set of bolt holes, but they are 3/4" apart so it stands to reason that last bolt hole would allow the motor to go over 1" above the pad.
If you've got more setback than the factory jackplate combo, then you can likely run higher.....
As they come from the factory with the 5.5" hydraulic and small spacer plate, using the middle set of holes set the propshaft about 1/4" below the pad when the jackplate is topped out. If you move to the 4th bolt hole, all the way up is about 1/2" above. That's been my experience with two 21's and 3 different motors. I haven't had the need to run on the last set of bolt holes, but they are 3/4" apart so it stands to reason that last bolt hole would allow the motor to go over 1" above the pad.
If you've got more setback than the factory jackplate combo, then you can likely run higher.....