40' Outlaw Upgrades - Twin 900Sc to 1000hp Duramax Diesels
03-30-2020, 09:09 PM
#561
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Thread Starter
Failure was a gear tooth, as suspected. So the props were obviously hooked up good enough to find the weakest link.. 
03-31-2020, 07:24 AM
#563
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On your drive depth Vs prop diameter struggles I agree w/the comments pointing at dropping drives.
Particularly pointing out the boat only sees half your prop diameter increases.
The other half is out of the water.
Ive done a ton of playing w/this on smaller boats and IMO, the biggest part of the equation effecting outcome is hull/rig weight.
On a flyweight, mid/hi HP rig, you can run stupid drive/prop heights.
When you start adding weight it changes drastically.
On heavier hulls I run my junk 2”+ lower than the rigs I’m reading about.
Also, if you’re running a bow heavy rig, and you’re using your wheels to carry the bow, they need to be in the water.
I see a lot of porpoising issues that I’d bet heavy are caused by the wheels not having a good enough bite to hold the bow in the air.
Another thing I don’t like about elevated heights on heavier rigs is getting it on plane.
A lot of them you have to break the wheels loose, fire wall the sticks and hope it rolls over before something breaks!
My guess is a lot of thrown blades come from this.
On my twin O/Bs I can watch the motors shake through this transition and it scares me every time.
If you watch videos you can see the blades load/unload.
Maybe the worst abuse they see?
Do we know that didn’t take out your gears?
Imagine the torque loading on those gears at the level you guys are at 😮
I know my junk/experiences are tiny compared to what you guys are engineering but physics is physics.
A bonus to lower drives/wheels is also drastically improved handling/performance everywhere else.
I can’t dock my twin O/B in a wind w/the motors up.
W/them down, my wife can dock it.
I can come on plane at 1/2 throttle.
Last thing I would add is, sometimes the experts are wrong.
Especially on a unique rig like yours.
Ive had twin O/Bs prove every performance tip wrong.
Rotation, toe, height, etc.
Sometimes you just throw the book out the window.
Particularly pointing out the boat only sees half your prop diameter increases.
The other half is out of the water.
Ive done a ton of playing w/this on smaller boats and IMO, the biggest part of the equation effecting outcome is hull/rig weight.
On a flyweight, mid/hi HP rig, you can run stupid drive/prop heights.
When you start adding weight it changes drastically.
On heavier hulls I run my junk 2”+ lower than the rigs I’m reading about.
Also, if you’re running a bow heavy rig, and you’re using your wheels to carry the bow, they need to be in the water.
I see a lot of porpoising issues that I’d bet heavy are caused by the wheels not having a good enough bite to hold the bow in the air.
Another thing I don’t like about elevated heights on heavier rigs is getting it on plane.
A lot of them you have to break the wheels loose, fire wall the sticks and hope it rolls over before something breaks!
My guess is a lot of thrown blades come from this.
On my twin O/Bs I can watch the motors shake through this transition and it scares me every time.
If you watch videos you can see the blades load/unload.
Maybe the worst abuse they see?
Do we know that didn’t take out your gears?
Imagine the torque loading on those gears at the level you guys are at 😮
I know my junk/experiences are tiny compared to what you guys are engineering but physics is physics.
A bonus to lower drives/wheels is also drastically improved handling/performance everywhere else.
I can’t dock my twin O/B in a wind w/the motors up.
W/them down, my wife can dock it.
I can come on plane at 1/2 throttle.
Last thing I would add is, sometimes the experts are wrong.
Especially on a unique rig like yours.
Ive had twin O/Bs prove every performance tip wrong.
Rotation, toe, height, etc.
Sometimes you just throw the book out the window.
Last edited by Twin O/B Sonic; 03-31-2020 at 07:26 AM.
03-31-2020, 09:09 AM
#564
Registered
On your drive depth Vs prop diameter struggles I agree w/the comments pointing at dropping drives.
Particularly pointing out the boat only sees half your prop diameter increases.
The other half is out of the water.
Ive done a ton of playing w/this on smaller boats and IMO, the biggest part of the equation effecting outcome is hull/rig weight.
On a flyweight, mid/hi HP rig, you can run stupid drive/prop heights.
When you start adding weight it changes drastically.
On heavier hulls I run my junk 2”+ lower than the rigs I’m reading about.
Also, if you’re running a bow heavy rig, and you’re using your wheels to carry the bow, they need to be in the water.
I see a lot of porpoising issues that I’d bet heavy are caused by the wheels not having a good enough bite to hold the bow in the air.
Another thing I don’t like about elevated heights on heavier rigs is getting it on plane.
A lot of them you have to break the wheels loose, fire wall the sticks and hope it rolls over before something breaks!
My guess is a lot of thrown blades come from this.
On my twin O/Bs I can watch the motors shake through this transition and it scares me every time.
If you watch videos you can see the blades load/unload.
Maybe the worst abuse they see?
Do we know that didn’t take out your gears?
Imagine the torque loading on those gears at the level you guys are at 😮
I know my junk/experiences are tiny compared to what you guys are engineering but physics is physics.
A bonus to lower drives/wheels is also drastically improved handling/performance everywhere else.
I can’t dock my twin O/B in a wind w/the motors up.
W/them down, my wife can dock it.
I can come on plane at 1/2 throttle.
Last thing I would add is, sometimes the experts are wrong.
Especially on a unique rig like yours.
Ive had twin O/Bs prove every performance tip wrong.
Rotation, toe, height, etc.
Sometimes you just throw the book out the window.
Particularly pointing out the boat only sees half your prop diameter increases.
The other half is out of the water.
Ive done a ton of playing w/this on smaller boats and IMO, the biggest part of the equation effecting outcome is hull/rig weight.
On a flyweight, mid/hi HP rig, you can run stupid drive/prop heights.
When you start adding weight it changes drastically.
On heavier hulls I run my junk 2”+ lower than the rigs I’m reading about.
Also, if you’re running a bow heavy rig, and you’re using your wheels to carry the bow, they need to be in the water.
I see a lot of porpoising issues that I’d bet heavy are caused by the wheels not having a good enough bite to hold the bow in the air.
Another thing I don’t like about elevated heights on heavier rigs is getting it on plane.
A lot of them you have to break the wheels loose, fire wall the sticks and hope it rolls over before something breaks!
My guess is a lot of thrown blades come from this.
On my twin O/Bs I can watch the motors shake through this transition and it scares me every time.
If you watch videos you can see the blades load/unload.
Maybe the worst abuse they see?
Do we know that didn’t take out your gears?
Imagine the torque loading on those gears at the level you guys are at 😮
I know my junk/experiences are tiny compared to what you guys are engineering but physics is physics.
A bonus to lower drives/wheels is also drastically improved handling/performance everywhere else.
I can’t dock my twin O/B in a wind w/the motors up.
W/them down, my wife can dock it.
I can come on plane at 1/2 throttle.
Last thing I would add is, sometimes the experts are wrong.
Especially on a unique rig like yours.
Ive had twin O/Bs prove every performance tip wrong.
Rotation, toe, height, etc.
Sometimes you just throw the book out the window.
Last edited by green lightning; 03-31-2020 at 09:32 AM.
03-31-2020, 01:11 PM
#565
Registered
Thread Starter
When that gear tooth decided to let go, I had the drives trimmed way up and the bow 6 feet in the air. They were diving deep and hooked up hard in an effort to gain speed. First thought was we struck something. Second thought was, BillyG is gonna kill me for trashing a pair of his race props.. I could actually envision Twisted Metal sporting a "Sponsored by Dave and Ken's Crazy BAJA Project" down the side this season... 
While relieved we didn't damage the props, I knew something wasn't happy with that approach to solving the situation. Really wished Billy was onboard that day for his experience with super high drives. But as well stated by Twin O/B above, the boat weight difference and our recent CG changes creates huge unknowns. Between a staggered 40' flat deck Fountain those props normally push, and 40' Baja OL with full cabin, there is probably 3000lbs and 6ft in CG difference.
On the way back to the dock, Dave and I discussed how impractical it would be even if you could figure out a "trick" to get it on plane as sets. Once ya add fuel, water, the hatch, three buddies, couple coolers of refreshments, it might sink enough to hook up, or not. Once ya burned off the fuel fuel and booze, you could find yourself fighting the same issue again. And for docking, better read that wind, because reverse was just slightly better than neutral on the sticks..
So even before finding the busted lower, we were in full agreement to lower the drives 2 holes and try again. At that setting they'll likely remain a tad higher than the factory 6's. These W have a longer skeg, so that should help docking if it's actually below the bottom of boat. Currently you'd be hard pressed to damage one unless you backed it up the boat ramp. :-)
While relieved we didn't damage the props, I knew something wasn't happy with that approach to solving the situation. Really wished Billy was onboard that day for his experience with super high drives. But as well stated by Twin O/B above, the boat weight difference and our recent CG changes creates huge unknowns. Between a staggered 40' flat deck Fountain those props normally push, and 40' Baja OL with full cabin, there is probably 3000lbs and 6ft in CG difference.
On the way back to the dock, Dave and I discussed how impractical it would be even if you could figure out a "trick" to get it on plane as sets. Once ya add fuel, water, the hatch, three buddies, couple coolers of refreshments, it might sink enough to hook up, or not. Once ya burned off the fuel fuel and booze, you could find yourself fighting the same issue again. And for docking, better read that wind, because reverse was just slightly better than neutral on the sticks..
So even before finding the busted lower, we were in full agreement to lower the drives 2 holes and try again. At that setting they'll likely remain a tad higher than the factory 6's. These W have a longer skeg, so that should help docking if it's actually below the bottom of boat. Currently you'd be hard pressed to damage one unless you backed it up the boat ramp. :-)
03-31-2020, 06:04 PM
#566
Registered
You touched on another variable I left alone.
If you set it up w/you and a buddy, light fuel load, empty boat other than that, perfect conditions, wind behind you, then come back on the Fourth of July w/the wife, grand kids, coolers, full tanks, it’s rough, and your heading into the wind to get on plane.........., and can’t....
Ugh
If you set it up w/you and a buddy, light fuel load, empty boat other than that, perfect conditions, wind behind you, then come back on the Fourth of July w/the wife, grand kids, coolers, full tanks, it’s rough, and your heading into the wind to get on plane.........., and can’t....
Ugh
04-01-2020, 03:11 PM
#567
Registered
Thread Starter
Yes you could actually feel a difference in them between upwind and downwind. To the point we even made long circles in an effort to take advantage.
I was actually thinking about trying again on a inland lake, since fresh water has less buoyancy than salt. If saltwater is good for 10mph on a 100mph boat, then maybe removing that condition would allow us to get up on top and see exactly where the prop shafts fall at speed. But in the end, the boat will live in saltwater so it's apples to oranges in the big picture.
I was actually thinking about trying again on a inland lake, since fresh water has less buoyancy than salt. If saltwater is good for 10mph on a 100mph boat, then maybe removing that condition would allow us to get up on top and see exactly where the prop shafts fall at speed. But in the end, the boat will live in saltwater so it's apples to oranges in the big picture.
04-03-2020, 11:56 AM
#568
Registered
Yes you could actually feel a difference in them between upwind and downwind. To the point we even made long circles in an effort to take advantage.
I was actually thinking about trying again on a inland lake, since fresh water has less buoyancy than salt. If saltwater is good for 10mph on a 100mph boat, then maybe removing that condition would allow us to get up on top and see exactly where the prop shafts fall at speed. But in the end, the boat will live in saltwater so it's apples to oranges in the big picture.
I was actually thinking about trying again on a inland lake, since fresh water has less buoyancy than salt. If saltwater is good for 10mph on a 100mph boat, then maybe removing that condition would allow us to get up on top and see exactly where the prop shafts fall at speed. But in the end, the boat will live in saltwater so it's apples to oranges in the big picture.
I just found this thread , and love it !! By watching the vids, it looks like your facing massive ventilation , when the boat wants to roll in plane , the drives are at the deepest location , where the hull pushes the water away in front of the drives , leaving the props with aerated water , so the high X , with having the props so high pulling air in , therefore no thrust. We had this with the old #4 and #5 , these drives don’t have a anti ventilation plate above the props , just like the Weissmans do , to cure it on a ssm4/5 we made a anti ventilation plate from 1/2 inch thick Ali , just about the size of a bravo 1 plate , we took the 1 inch spacer and milled off the last 4 inches 1/2 inch deep .Drilled the 2 holes on the back so the mounting bolts Go thru , and ready she was , and glide into plane with ease .
no idea if there is a way to do this on a weissman drive .... before we did all this we actually pulled the boat in plane with another boat , and a 50 ft rope, we just wanted to find out if the non plane issue was the only problem , once pulled in plane it was all good , so we decided to focus on the main problem
04-04-2020, 12:18 AM
#569
Registered
Thread Starter
Thanks much for the input. Glad you enjoy our little 4yr R&D project.
Your experience sound exactly what we were seeing. With the six blades and swim platform off, I could see the water in front [between] the drives was very turbulent as speed increased. From what I could tell it was related to the pick up tubes protruding below the bottom. But whatever the cause, it looked like a washing machine before the props ever reached it..
On advice of my experienced racing buddy, I tried to keep the tabs neutral to limit the disruption of flow on the outside. Using the tabs to help aerate props is a technique we discussed before testing that day. You could actually feel it was worse with tabs full up or down vs neutral.
Funny you mention pulling the boat up on plane to get past the issue and verify running height. On day one with the 4 blades, couple guys from Innovation were out in a 42 Fountain with trips testing, They were stopped with hatch up keeping nose into the 25 knot winds and whitecaps, so I pulled up and yelled over "Can we get a tow up to 40mph." Jokingly knowing they were in a clients boat, but I sure wouldn't have refused if they said yes...
Your experience sound exactly what we were seeing. With the six blades and swim platform off, I could see the water in front [between] the drives was very turbulent as speed increased. From what I could tell it was related to the pick up tubes protruding below the bottom. But whatever the cause, it looked like a washing machine before the props ever reached it..
On advice of my experienced racing buddy, I tried to keep the tabs neutral to limit the disruption of flow on the outside. Using the tabs to help aerate props is a technique we discussed before testing that day. You could actually feel it was worse with tabs full up or down vs neutral.
Funny you mention pulling the boat up on plane to get past the issue and verify running height. On day one with the 4 blades, couple guys from Innovation were out in a 42 Fountain with trips testing, They were stopped with hatch up keeping nose into the 25 knot winds and whitecaps, so I pulled up and yelled over "Can we get a tow up to 40mph." Jokingly knowing they were in a clients boat, but I sure wouldn't have refused if they said yes...
04-04-2020, 02:12 PM
#570
Registered
I m sure you can find somebody that is willing to pull your boat in plane , we just wrapped it around a cleat ( big one ) and hold the end , all it took was a little pull , and as soon as the nose dropped , I felt the props bite , and loading the engine, I let the rope go , and in plane we were .
