Hard starting Yamato 102

[ZUL8TR]

The traps now need to be trimmed. As I noted in my sketch to you the traps should be zero at the rear and your pic shows some height. Thus air is lifting the rear and causing squirley operation for your hull. First start by trimming traps from sponson to zero at the rear. Test. Then trim some more little by little as Bill VS suggests. My Wetback worked best with zero at rear and a bottom up concave trimmed into the traps to spill the air just right. Took time to perfect to get the boat to float just right. You still need to get in the rear with head down.

[johnsonm50]

It actually doesn't look that bad but of course a vid wont show what the driver senses. Now that you are experiencing air its no surprise you'll thinlk it loose. Like posted a little trim will help. Your fin position will be more critical too, all the way down & forward I've found to make my C Bezoat wiggle entering a turn. Letting it hang back a little fixed it tho. Another thing to do is add a spray rail on the starboard rear, this will catch some of the spray & redirect it down giving that corner slightly more lift & stability. You have a nice finish on the boat however some gain can be had in sanding the last 3' of the bottom rear across direction with 400 grit just to dull it. it will bw slipperyer than shiney. Get used to the eqiupment.. its good to see you got it. Driving is part of how the boat will handle.. the best rigged boat won't run right not driven right...[this is one of those hypocrite moments] but test running further back & hunkered down for more lift & less drag. Lookin good as you go.. Good Luck

[BillCNC]

ZUL8TR and ALL,

Yea, .. it actually is about 1/8th proud at the transom. My sponson's are set in 1/8" from the afterplane, So I had to cut a notch for it so the air trap pieces could be moved inward and would be flush on the inside in relationship to the sponson's. In doing so, ... it raised the air trap pieces 1/8" and it would have been more of a hassle to try to trim the pieces on the table saw and I knew I would be planing them down after the test run. I thought about trimming before hand, but the epoxy wouldn't be dry in time so that's what I ended up with. I'll trim them down and reseal them.

I know in the video, I am still sitting to far forward, ... but when I went to scoot back, ... the back end of the boat was ALL OVER THE PLACE, ... sitting forward was the only position that was controllable and not send the boat in a tizzy fit.

I thought the back end was prop walking because if you left the steering wheel a little loose in your hand, ... it wanted to turn the boat left, ... and I mean LEFT!

The prop shaft is set at 3/4" below the bottom and the incidence is set at zero. I was getting some water out of the tubes but it might have acted like the prop was to high because of the gained lift from the air traps. Not sure if I should lower it a little as the prop was cavitating again trying to get on plane.

[ZUL8TR]

set up

ZUL8TR and ALL,

Yea, .. it actually is about 1/8th proud at the transom. My sponson's are set in 1/8" from the afterplane, So I had to cut a notch for it so the air trap pieces could be moved inward and would be flush on the inside in relationship to the sponson's. In doing so, ... it raised the air trap pieces 1/8" and it would have been more of a hassle to try to trim the pieces on the table saw and I knew I would be planing them down after the test run. I thought about trimming before hand, but the epoxy wouldn't be dry in time so that's what I ended up with. I'll trim them down and reseal them.

I know in the video, I am still sitting to far forward, ... but when I went to scoot back, ... the back end of the boat was ALL OVER THE PLACE, ... sitting forward was the only position that was controllable and not send the boat in a tizzy fit.

I thought the back end was prop walking because if you left the steering wheel a little loose in your hand, ... it wanted to turn the boat left, ... and I mean LEFT!

The prop shaft is set at 3/4" below the bottom and the incidence is set at zero. I was getting some water out of the tubes but it might have acted like the prop was to high because of the gained lift from the air traps. Not sure if I should lower it a little as the prop was cavitating again trying to get on plane.

I would lower till you get the traps and lift and turning worked out.

[mercguy]

ZUL8TR and ALL,

Yea, .. it actually is about 1/8th proud at the transom. My sponson's are set in 1/8" from the afterplane, So I had to cut a notch for it so the air trap pieces could be moved inward and would be flush on the inside in relationship to the sponson's. In doing so, ... it raised the air trap pieces 1/8" and it would have been more of a hassle to try to trim the pieces on the table saw and I knew I would be planing them down after the test run. I thought about trimming before hand, but the epoxy wouldn't be dry in time so that's what I ended up with. I'll trim them down and reseal them.

I know in the video, I am still sitting to far forward, ... but when I went to scoot back, ... the back end of the boat was ALL OVER THE PLACE, ... sitting forward was the only position that was controllable and not send the boat in a tizzy fit.

I thought the back end was prop walking because if you left the steering wheel a little loose in your hand, ... it wanted to turn the boat left, ... and I mean LEFT!

The prop shaft is set at 3/4" below the bottom and the incidence is set at zero. I was getting some water out of the tubes but it might have acted like the prop was to high because of the gained lift from the air traps. Not sure if I should lower it a little as the prop was cavitating again trying to get on plane.

if you let off the grip on the steering wheel and it immediately wants to turn left you have the steering TOO LOOSE......BTW, it should want to turn left ......

[johnsonm50]

Right, left.. if it prop walked it would try to turn right, if it gets too far the boat will tip up over the fin & you'll be in the water. The motor will rev 1st from breaking free. btdt

[S Henderson]

angle

Well here’s my 2 cents. Before you cut on the air traps I would do what ZUL8TR says in his post about the angle of prop shaft. From what you say about it being hard to plane off and braking loose on the straightaway way
it sound like the motor is to high. Also from the pictures it is kicked out. You may need to drop it more and kick it under.
Stan

[BillCNC]

I would lower till you get the traps and lift and turning worked out.

How far?

[BillCNC]

if you let off the grip on the steering wheel and it immediately wants to turn left you have the steering TOO LOOSE......BTW, it should want to turn left ......

My steering cable tightening procedure is;

Loosen the coaming clamp on one side, ... pull the cable end with vise grips and then tighten. Do the same to the other side, ... then do them BOTH all over again.

I thought I had them to tight. The steering is pretty tight, to the point you really have to try to turn the wheel by trying to move the motor by hand.

Is that tight enough?

[BillCNC]

If you guys look at this video, ... http://youtu.be/_9UU5MjQz9E at the :15 second mark, ... you can see when it started getting violent, .. the sponson's started rocking from one side to the other, ... that's when I cut the throttle.

Also in this video http://youtu.be/g7lzalnv0u8 at the :4 second mark.

You can even hear it happening in both videos as the motors RMP gets all jumpy. To tell you the truth, ... it was not the smartest thing to do to try to recreate the violent shaking after going through it the first time. But it's the only way I could show you so I am able to get advice on how to deal with it..

[ZUL8TR]

height

How far?

I recall that you have the shaft at 3/4", lower to prop shaft 1-1/4" below bottom and make the shaft dead parallel to the bottom. Report the rpms from the tach.

[ZUL8TR]

steering

My steering cable tightening procedure is;

Loosen the coaming clamp on one side, ... pull the cable end with vise grips and then tighten. Do the same to the other side, ... then do them BOTH all over again.

I thought I had them to tight. The steering is pretty tight, to the point you really have to try to turn the wheel by trying to move the motor by hand.

Is that tight enough?

That sounds tight. It should be tight enough such that you can turn the boat without manhandling the wheel.

[ZUL8TR]

action

If you guys look at this video, ... http://youtu.be/_9UU5MjQz9E at the :15 second mark, ... you can see when it started getting violent, .. the sponson's started rocking from one side to the other, ... that's when I cut the throttle.

Also in this video http://youtu.be/g7lzalnv0u8 at the :4 second mark.

You can even hear it happening in both videos as the motors RMP gets all jumpy. To tell you the truth, ... it was not the smartest thing to do to try to recreate the violent shaking after going through it the first time. But it's the only way I could show you so I am able to get advice on how to deal with it..

The rocking could be cross waves hard to tell, the high revs is the prop getting loose. Lowering will solve that.

What is the transom angle on your hydro?

You will get this worked out be patient.

[BillCNC]

Pete,

Oh, ... I'm patient, ... and am VERY thankful of the group here and for all it's help.

I was going to put her away for the winter and continue to figure it out in late February or March, ... but since were on a roll and there are people to help me, ... I can brave the cold water, ...

It wasn't cross waves that tried to do me in, ... as you can see, the water was pretty flat. Before the air traps, ... the boat ran smooth on the water with no ill effects, ... now it is just really squirrelly.

I was thinking another .750, ... but a total of 1-1/4 sounds just as good.

Bill

[mercguy]

My steering cable tightening procedure is;

Loosen the coaming clamp on one side, ... pull the cable end with vise grips and then tighten. Do the same to the other side, ... then do them BOTH all over again.

I thought I had them to tight. The steering is pretty tight, to the point you really have to try to turn the wheel by trying to move the motor by hand.

Is that tight enough?

to properly tighten the cables you need to have the motor tilted up somewhat, then snug the cables up, then when motor is let back down, the cables will be properly tightened.....you sho