Now that i have got it running right my slingshot starts to jump from side to side at around 85 to 90, is that what you call chinewalk, is it fixable? It feels real dangerous.
Fred

it shouldn't be doing it at that speed, ck drive alignment, or slack in the hinge pins,grab the skeg move it side to side see if any slack. What drive foot, gear ratio,props,RPM,horsepower,wind and water conditions???????

my center to center prop,is 46 13/16. its 3/8 toed in,It was 13/16 I have to cut the tie bar to get it closer to O.Make sure the drives are zero/level to the bottom not the notch,also there is Salk in the indicator lines, I trim up to around 2.1/2 and if I go past ,I go back in and start over because if to go past it will be off over a 1/2 a number,which is almost a 1/2 inch diff at the drive.do the same way with the tabs,When I try and run over 100 I set the drives and want change them,depends on water (1foot chop) is best, When I run it up to speed ,drives set, I roll up to 90 still accelerating to 95 .see how it feels and to the wood.if its going to run a # ital hit 101 pretty quick the 102.the 102.3 I held it longer.Some days you can tell its acting up and isn't going to run 100plus.Any cross wakes,side wind,full water tank will throw it in to a walk above 90.

Chinwalk,to me it is like if the boat is on a center pad balancing on a BB, when if falls to the side and back to the other side, thats the walking, its like bouncing from rub rail to the other rub rail, It takes time learn how to drive it, keeping it straight, up right,like balancing it,using the steering wheel to catch/counter act to keep it from falling off ,A lot of people say use a little tab, I did in the beginning, I learned how to keep it from chinwalking and I'm using no tab!!Above 100 it porpoises pretty good,basically over trimming it, but it faster that way, bumping the trim down any,will slow it down!!Ive never done any mods to the props, they say that will help.Need to get some Stearn lift out of it, some times ya can fell it snaking,like its getting on top of the props walking sideways.If I could get the porpoising out I think it would free it up.next thing for me is B Blades labing

Im rambling

picks around 99.8-100

I am running Bravo XR 1.5 ratio 32p bravo props 630 hp 575sci at 5200 - 5500 rpm ( hard to keep my eyes on the tachs as i bounce from side to side dicing with death)!
I have not checked the geometry yet but will do. One thing i have noticed is that one prop keeps working loose and they are not in great condition, they are definately not the labbed props that the boat came with originally, i will be speaking to B Blades or Julie. The motion you describe is exactly what happens to me, flat sea to moderate chop, adding a little flap helps to stabilise a little but does not help max speed (92 so far)

I would start with props!!! In flat water mine want run good , it porpoises worse in flat.like its stuck to the water.

In time you'll learn how to steer it to keep it from walking,I'm guessing with no flaps will be around 2-3mph, then the props,because you really don't know what been done to them, even is repaired

People have told me not to turn or chop the throttles if it goes into a chinwalk.Once mine starts I get out of it.its all in the steering of it,If ya don't feel comfortable don't push it,I'm told it could spin?

Do you have anybody over there you can barrow some 30-32 4blade stock merc bravo one props to try??

Also remember used labed props were made just a boat,most labbing I would assume it would have stearn lift in the prop,the Hustler has too much to start with,and the higher speed its lifts even more, you can see on my pick the outside chin by the speed tube it out of the water,i would say the tabs are 4-6in above the water.

Fixable? Prob not,they claim ya can cut some of the center strakes out 18-24 inch,they say it helps. Joe/Hustler says do not do it,it cuts into the stringer and you'll have to add to the inside more glass for support,Also its cuts down on stearn lift which solws it down?I only heard of 2 people/boats that done it, no reports Werther it helped.

From what I've seen with the 388's, the strakes are an issue if you can get the boat to go fast enough to make them an issue.

I've had several customers of the very early 388's that were built prior to when Joe took over and the customer cut the strakes and addressed the issues inside the boat with the stringers. Boats built after Joe took over are easier as Joe made the stringers solid removing any stringer concerns. They worked out great. 750ish hp, 108-112 mph.

Cutting the stringers will make a positive benefit in the area of chine walking. Modification is basically a need when running over 100 mph.

For speeds In the 80's I would just add a set of 380 bottoms ito your K-Planes. Timing is the key to the boat. You have to set the tabs prior to the speed that causes a porpoise or chine walk as when they start there is no adjustment to stop the action but prior input will prevent it from happening.

Rik-That's good feedback on the strakes and tabs. I'll try presetting the tabs next season if my boat doesn't sell. I put the 380's on my Slingshot 3-4 years ago. I've got Merc 800SC's with #5 SpeedMasters. I don't know if the larger skeg together with the motors being farther forward to make room for the transmissions helps the stability. It does get loose,but I don't seem to get the violent side to side rocking. I've personally seen the Black Cloud Slingshot run with those Arnesons and it certainly looked stable. That was an early Slingshot and I recall someone saying that Ritchie cut the strakes.

Yea, Ritchie is the first one to cut the strakes after the boat got out of shape in the 140's.

You will need to drag a bit of tab before you reach the speed where the problem starts.

Rik thanks for the advice.Joe was giving me some of this info, he said around 03+ they made the chine solid then the stringer on top of it,so ya don't cut into the wooden stringer ,Joe said its a big job,basically told me don't do it. I am figuring I don't have much left in it like it is?

Rik will the chine mod help with the porpoising? I am able to pretty much keep it from chine walking around 100.Its like its trying to carry the nose then drops it,If I use any tab it will slow it down, but it stables it.I usually set the trim then try it,in flat water it just porpoising,but its faster that way, If trim down any,it kills it about 2mph,In about 1ft chop it gets on top and is not as bad,I have not tried turning the props in,wonder if that will settle it down some?Thanks,Rob


Messing around Sunday,short clip


http://s19.photobucket.com/player.sw...fs=1&os=1&ap=1


[YOUTUBE]http://www.youtube.com/watch?v=Qg7JhjgSd7Y[/YOUTUBE]

There are certain hulls that for some reason porposie.

I know that a few of the race boats they built were cured with the Rocker Plates.

Removing the strakes will lower the rear a slight amount. Have you tried different rake propellers? The less rake the more stern lift and this should help with the porpoise or go the opposite direction and get more rake to see if you can hold the bow better.

From what I've dug up, I've learned that...

A Bravo 1 has 25 degrees of rake
A Maximus has 30 degrees of rake

Hering is around 22 degrees of rake some + - from that #.

I do not know the rake of they hydromotive

For the Arnesons, we ran a standard 15 degree rake 5 blade propeller, but we have the option of a 15 degree, 18 degree or 21 degree rake if needed.

Do you know where the CG is on the boat?