Power Slot "Type" of Mod

[SacRiverRat]

Are there any specific boat tests on these things? I'd like to see some actual data, and am interested in what you felt Joe. ... not that I understand why it would work - I don't get it, but would like to see if there are test that show it too

Could have been some other weird factors for you like weather, water conditions, sound of the exhaust etc.. that made it feel faster out of the hole (not that I don't believe you )

[edwin]

I had talked with Vince at skidim to put together a parts list to convert my SLXi to a gear reduction boat. At the end of the day, wasn't really that big of a job. Think the parts bill (new parts) came to somewhere around $3k.

[WakeGirl]

edwin, I'm guessing that was to modify your existing tranny, am I right?

[edwin]

New trans and associated hardware, including new prop

[UWSkier]

Gear reduction lets you spin the prop fewer times over the same distance travelled. Fewer revolutions = less slip = greater efficiency from a hydrodynamic standpoint. Remember, we're not dealing with a solid here. If we were, the argument that you can simply change a prop to overcome the gearing difference would hold water (no pun intended).

Edited April 15, 2005 by UWSkier

[Slider]

OK I think I can explain why gear reduction works using automotive terms which hopefully everyone will understand. If you have a drag car and a limited budget you can run smaller diameter drive tires to increase your torque and hole shot times, but it reduces your top speed. (basically what a 1:1 tranny is doing because no comp boat is geared for top end anyway) If you want to go even faster with the same car you reduce your gear ratio in the drive differential and put bigger tires on that have more traction. This keeps your overall gear ratio the same as small tires and stock tranny, but allows for more traction and the same top end. You are able to harness your power more efficiently on the bottom with out losing the top end capabilities. I think this is the same with a boat, find a way to get more hole shot without losing top end.

Joe

[UWSkier]

Another reason gear drives are more efficient is "effective pitch." The propshaft angle on these boats is inherently inefficient. For greater efficiency, the prop shaft should run parallel to the surface of the water. There's a certain amount of "inefficiency" introduced with each prop rotation in this configuration. If you can reduce the number of revolutions, you can reduce some of the inefficiency. This is probably why the farmer's son in Peter's post saw such great performance out of his Response redux.

As far as Nautiques go, they're under-propped overweight tanks with extremely inefficient hulls.

Edited April 15, 2005 by UWSkier

[mrothwell]

the other difference is that a 14" prop has more surface area than a 13" prop, so it will have better "traction"/less slip. This is why a 4 blade will have a better holeshot than an equivalent 3 blade.

Don't make me go into the "prop column"

If that comment doesn't get Rutat out of hiding, nothing will.

[M3Fan]

The hole shot is not the only reason for the redux. The wake behind the boat and the boat's speed holding capability once at speed are also reasons. This is why CC still has the reduction trans even with 375, 330 hp motors. They don't need the trans for holeshot. The larger prop spinning slower offers different wake characteristics. Also, in the CC with reduction, the gearing naturally allows the ouput shaft to be angled out of the trans. This way the engine sits level- which , let me tell you, makes many repairs including taking the trans out MUCH easier. As a side note, notice that MC now offers almost the same redux ratio as CC now...

[Wkerat]

Would I be correct in assuming that this is what MB's two speed does? It gives you a redux for efficiency out of the hull and a regular gear for all around. If so how do they get the prop to work without over revving the motor?

Also, do we know why Malibu does not offer this?

[VinRLX]

Bob Alkema said no.  End of story.

<{POST_SNAPBACK}>

[Wkerat]

Interesting....Now that I read Peters post I have to agree. My buddy and I ran his 04 response lxi with the monsoon next to my 04 vlx with the monsoon and they accelerated identical and had the same top end. Neither would pull away, even with the added weight of the vlx.

[WakeGirl]

Wkerat,

The MB is a different tranny altogether, it's an actual shifting 2 speed transmission. You take off in first gear then when you reach a certain rpm you shift into 2nd.

[VinRLX]

Tracie, what's the downside to that transmission?

[WakeGirl]

I haven't seen any, other than the cost. In theory, there are more moving parts, it would be a bigger, heavier housing, so the KISS principle kind of gets left in the dust. But everything that I've read about them indicates that it's a well engineered product. It would be rather pointless in a ski boat (& actually have some detrimental effects with the size & extra weight, but that's just my theory, YMMV), but in a big wakeboard boat running huge amounts of ballast (the B52 has 2100 lbs stock) it would be a great solution, not only from a get-the-boat-out-of-the-hole standpoint, but from a gas mileage/consumption standpoint as well.

I would bet that in the coming years as boats get bigger & heavier, more companies will look at this & try to integrate it to their programs.

[VinRLX]

Thanks. Be kind of cool in a ski boat though. . .enough grunt to rip the arms out of five skiers and enough top end to do 55!

[whiteVLX]

I wonder if boats really are going to get bigger and heavier. With the current state of affairs with gas pricing, it's got to be hitting the boat manufacturers. I wouldn't be surprised if they start looking into options to improve fuel efficiency. Be it better engine technology or reducing boat size and weight.

Thinking of technology, did any of yall see the article about Indmar testing a catalytic converter for boats? It was pretty interesting reading and from the sounds of it not to far away from being reality, 2- 3 years maybe.

[VinRLX]

Seems like a necessity with new regs coming down the pike. That's why we need more horsepower in these boats.

[WakeGirl]

Steve, I think that you're right to a point, but I was talking more about the higher end of each brand's line. Look at each brand, with the possible exception of CC, with each design change the big boats get a little bigger & a little heavier (example, VLX & SLXI for the '05 Malibus). Most people in that price range don't care much about the price of gas (okay, they care less about the price of gas). Personally I'd love to see it taper off, but the demand in that market is for more room, more ergonomics. Companies like Malibu will continue to give it to people until sales start to die off. Personally I'd love to see this trend stop in its tracks (not a fan of big boats), but until demand dies they'll keep designing them bigger & bigger.

Jack, not more hp we have plenty, we need more torque - stroke those engines!

[Wkerat]

I think the gas prices are hurting new boaters and smaller craft more than the higher end boats. When someone throws down 30k on a response, or 50k on a vlx, they can usually affored the gas. It is the young family or person that just wants a boat to get away who is getting hammered.

[WakeGirl]

I think the gas prices are hurting new boaters and smaller craft more than the higher end boats.  When someone throws down 30k on a response, or 50k on a vlx, they can usually affored the gas.  It is the young family or person that just wants a boat to get away who is getting hammered.

Totally agree & IMO the gap is only going to get larger.

[whiteVLX]

Good point on the fuel Roy.

I agree with you to a point Tracie, but it seems like it's not just the biggest models that are getting bigger, it's pretty much all of them.

Edited April 17, 2005 by whiteVLX

[WakeGirl]

Yep, the biggest models just seem to stand out more I guess.

[whiteVLX]

Yep, the biggest models just seem to stand out more I guess. 

<{POST_SNAPBACK}>

Ain't that the truth, I mean look at the WS LSV

[Wkerat]

I agree. I saw a line at the dealer today with that went like this. vlx, lsv sportster, vride, response lx, response lxi. The sportster looked like a baby boat next to the vlx and lsv and so did the response lx. It looked like the transom height was double the sportsters on the lsv. But then again they had 4 25 foot boats from other lines nearby and a 29 foot cobalt for a lake that really is ideal for a 22 foot boat.