Whirl-A-Way in a cruiser?

[lenmann]

Noob question and I am sure I have seen a thread on this subject but damned if I can find it. I have tried every spelling and hyphenation combo of Whirl-A-Way I can think of with no luck.

Why don't Cruiser type v-drive boats equipped with automatic transmissions (think t-400) need a Whirl-A-Way type safety device to prevent sudden deceleration in the event of a catastrophic engine failure or other such event that might suddenly stop rotation of the prop at speed?

 

[rightytighty]

Pretty sure whirl away and Reverse on the trans are not compatible..

 

[lenmann]

That makes sense.

So does the trans "free wheel" without a torque converter?

With as many fast Schiada's as there are out there I gotta believe someone has asked and answered this question.

I have never seen a Whirl-A-Way in any of the build threads either.

 

[ONE-A-DAY]

A cruiser just isn't going to be going fast enough to benefit from the whirl away kicking in during a catastrophic engine failure

 

[AzGeo]

A cruiser just isn't going to be going fast enough to benefit from the whirl away kicking in during a catastrophic engine failure

Didn't know that ............

 

[rightytighty]

That makes sense.

So does the trans "free wheel" without a torque converter?

With as many fast Schiada's as there are out there I gotta believe someone has asked and answered this question.

I have never seen a Whirl-A-Way in any of the build threads either.

That's a yes- but answer. Yes, but what if the trans locks up? It comes down to whirl away is safer but reverse is pretty damm handy.

 

[lenmann]

A cruiser just isn't going to be going fast enough to benefit from the whirl away kicking in during a catastrophic engine failure

How fast do you have to be moving to benefit from the use of a Whirl-A-Way?

 

[AzGeo]

That makes sense.

So does the trans "free wheel" without a torque converter?

With as many fast Schiada's as there are out there I gotta believe someone has asked and answered this question.

I have never seen a Whirl-A-Way in any of the build threads either.

When the 'front oil pump' in an automatic trans stops turning (coupler and input shaft stop turning) the entire transmission will lose oil pressure and then begin to 'freewheel', but it's never instantaneous, and therein lies the problem .

When an auto trans is used in a cruiser with a 'driveshaft' (of some substantial weight) , and the 'trans lets go', (engine still OK) the rotational momentum of the rotating mass, just keeps turning for a split second (or more) and that is enough to destroy any means for the trans case to stop the internal parts from continuing to rotate . It just pukes oil and parts all over the place, and hopefully does not lose the driveshaft and yoke .

From my experience, using an automatic trans does not take the place of a whirl-a-way .

Use of a 2 blade or 3 blade prop also affects boat control under 'failure conditions' .

Most cruisers without a whirl-a-way will 'bow steer', or 'lift the tail and the nose will hunt' (hard to steer) when the prop STOPS at high speeds . Balancing the gross mass for this kind of event seems to be the most effective way to 'keep control under emergency conditions' .

If you go fast off by yourself, away from others and the shore, you should have no problems . Traffic, shore, under water obstacles, and driver panic are the areas I try to avoid when going fast anyway .

Some 'cruisers' may become unstable at 75 MPH under these unusual conditions, others at much higher speeds, and so I always use a rudder of AT LEAST a 12" depth, which helps control the boat .

For the past 35+ years I have been asking; "Do you want a Ferrari or a school bus "? "You can't afford both" .

 

[AzGeo]

most of the 'couplers' used for automatic transmissions in boats are either; 'spool with drive plate', or '3 fingers' . Both are direct, and turn the trans oil pump and input shaft at the same speed whenever the engine is running . So neither is a clutch, or a sprag, but 100% coupled 'motor to trans' .

Some will still use 'solid welded torque converters', but most have gone to the couplers above . The welded torque converters, are '100% coupled' so they are just extra rotating weight, and not as strong as the couplers .

 

[lenmann]

Thanks George, that is just the kind of insight I was looking for.

Like many things in life, you can't have it both ways.

 

[AzGeo]

This deal runs in the 100's + ^ all the time, with no whirl-a-way, and little chance of losing control during a failure .

Drove with the owner to show him what it does with a 3 blade prop slowing from WOT to 20% throttle, BEFORE he took the boat home .

NO, I did not ride in the bow during those runs ......... HA HA