Custom/Hybrid Pump/ hull bench racing.

[tom21]

So I've had a conversation that got me thinking. When I pump swap an fx1 there is a marked improvement. On the first hull made the owner had a spacer made and set the pump back to be able to use the sj driveshaft. I've ridden both hulls. But not back to back. I'm barely a rider so it wouldn't have mattered anyway. I got asked what would happen if I just set the pump back?

So I've been chatting with some friends and I still can't wrap my mind around the pros and cons. Or will it be the same ride?

The benefit I can understand is the nozzle being more exposed giving more steering response.

Part of me worries that I'm lengthening the hull c.o.g and that will plane it down more? But if it does it's not something I can feel as prohibiting the nose from popping up and the hull being just as buoyant feeling.

Moving the intake back changes the handling how?
Does extending the tunnel help with keeping the pump hooked up at all?

So help me out and explain it like I know nothing so I can wrap my mind around this

Move tunnel back 2 inches vs extended pump

Seems like the new rn sj moved the pump back iirc? But I've only ridden that in stock form on flat and it wasn't as fun as earlier rn or sq.

The main reason I'm asking is to use a sj pump with the driveshaft. Upgrade. Having a ring made is not easy for me and while changing the mold at this point isn't easy it's a one a done. I also realize the cable is an issue. Right now I'm just trying to see this working in my mind. How it acts and what effects what. Help me out guys.

Thanks

 

[Sanoman]

l have one of your pump tunnels in my fx1 conversion. Very satisfying ride, but did have to have a shorter driveshaft made in order for it to work. Haven’t rode @hornedogg79 tom21 package, but he has rode mine and his so he might he able to give some good feedback!

Would like to hear his opinion

 

[yamanube]

I feel like there is a tradeoff on the pump setback. One thought is that moving the pump back increases leverage on the hull and increases steering response. On the other hand it would seem it could have a similar result as a longer wheelbase and increase turning radius.

 

[Sparkplug]

Pushing the nozzle out further, combined with moving the pole bracket forward, is hands down the number one way to change the handling of a ski. For the positive in my opinion. But alot of others disagree

Beware. Most riders have a hard time riding hulls with the nozzle sticking out. Most people will tell you it will hurt your back or not be able to be rec ridden. Dint listen to these people, unless you yourself are a basic rider. In which case. I would stick to a more tame style of riding and not chase something out of reach.

 

[yamanube]

Pushing the nozzle out further, combined with moving the pole bracket forward, is hands down the number one way to change the handling of a ski. For the positive in my opinion. But alot of others disagree

Beware. Most riders have a hard time riding hulls with the nozzle sticking out. Most people will tell you it will hurt your back or not be able to be rec ridden. Dint listen to these people, unless you yourself are a basic rider. In which case. I would stick to a more tame style of riding and not chase something out of reach.

Most hulls achieve nozzle stick out by reducing hull length, this is not what he is proposing. Unless the hulls you are referencing are using a longer driveshaft to achieve the pump setback.

 

[Sparkplug]

I'm simply stating that if you have a hull. Ride it. And then push the nozzle out further. Without changing anything else on the ski. It will change the handling for the better if the rider can adapt.

There is obviously a point where it turns into a long log trying to pivot through the water and the benefit is lost. But on a fx1, a naturally unstable hull, it would be an improvement to move the nozzle, or entire pump, towards the back.

 

[schicks]

I added an extra wear ring to one of my hulls, i was really happy with the result. Pics are in the product release section under inverse hull...