Tunnelstuff in Norway

[Joern Markset]

Had to test a new prototype of silencer for the Salisbury pipe, it made a big difference, but still a little loud.

 

[GraysonTaylor]

Is the gear drive an over drive or an under drive?

 

[Joern Markset]

Is the gear drive an over drive or an under drive?

Underdrive, at the moment the pinion is 20Z and the spur is 29Z, ratio 1,45:1

 

[Julio Almazan]

Yes, powertrim is very effective. However, to use it properly in a race you will need to be 100% on target when trimming in before a turn.
If you wanna use it for finding «the sweet spot» while testing it is very effective, boat is responding immediately exactly like the fullsize. Give it a try

Thanks

 

[GraysonTaylor]

That ratio takes 30k rpm down to just over 20k. I thought I once read that 20k was the best efficiency for a prop, but I can't remember where... keep us posted!

 

[Joern Markset]

That ratio takes 30k rpm down to just over 20k. I thought I once read that 20k was the best efficiency for a prop, but I can't remember where... keep us posted!

You are right, most props have very high slip percentage on high rpm. I experienced that when I was deep into eletric tunnels. for the Octura X series the slip increase drastically when you pass 30K rpm. Even from 25K the slip starts to increase.
I`m now reading close to 38K rpm on the engine. Will shorten the header a little bit to see if I can reach maximum rpm around 42K.
I have allready enough speed, and the acceleration is fantastic, so it will just be a bonus with some extra rpm`s.

Also for the NR .46 I think gear will be a good solution, they work much better with a little less load and high rpm.
Disadvantage is the extra weight you have to carry on the transom...

 

[Julio Almazan]

Hi:

Yes, powertrim is very effective. However, to use it properly in a race you will need to be 100% on target when trimming in before a turn.
If you wanna use it for finding «the sweet spot» while testing it is very effective, boat is responding immediately exactly like the fullsize. Give it a try

I'm still trying to make a system similar to yours, thank you.
If you have more pictures of your model, I am grateful to posted them here already.
Some time ago, I had a car accident and I´m in rehab... When I´m better, I'll start building and posted here.
Thanks for all.

 

[Joern Markset]

Hi:

I'm still trying to make a system similar to yours, thank you.
If you have more pictures of your model, I am grateful to posted them here already.
Some time ago, I had a car accident and I´m in rehab... When I´m better, I'll start building and posted here.
Thanks for all.

Don`t think I have more pics than you can find in post #59 https://www.intlwaters.com/threads/tunnelstuff-in-norway.72995/page-3#post-712547
It`s been quit some time since that boat was wet as there is new stuff and ideas coming up constantly...
At the moment I`m putting my effort into gearboxes.
Wish you a fast recovery.

 

[Christian Lucas]

Hi,
here in Europe the geard drive is very comon used. In FSR duration they run up to 90 size engine with gear. They use only a very small gear ratio of 1,2 - 1,3 : 1 , so the engine has a little moore punch out of the corner.
The smaller engine go with higher gear ratio 2 : 1 and higher. Reason is to drive the bigger propeller dia that has less slip and better acceleration and pushing performance in and out of the corner, not for higher top speed.
Very nice drive with the geared outborder setup.

Happy Amps Christian

 

[Kris Flynn]

Have you tried a small diameter carby? I have a KRE 10mm which is VERY quiet compared to the 11mm orlic.

LMK if you want to try it? No proper testing to compare performance sorry

 

[Joern Markset]

Got some time to assemble the .28
Gonna be interesting to see if there is something in it

 

[Jerry Dunlap]

What is your gear reduction ratio? Nice looking work.

JD

 

[Joern Markset]

What is your gear reduction ratio? Nice looking work.

JD

At the moment 1.45:1
Can probably gear a little higher like 1.30:1
Need to see if there is any torque in it

 

[Joern Markset]

I found a sufficient hull for the NR .28
Not many hours left before I can do a test run

 

[Manuel Xavier]

The WSB hull will perform well with the geared outboard

 

[Joern Markset]

The WSB hull will perform well with the geared outboard

So you have allready tried it, how does it perform in the needle sharp turns?

 

[Manuel Xavier]

In Portugal we use to race in a triangular circuit and the hull turns well. I added stumble blocks

 

[Grimracer]

Got some time to assemble the .28
Gonna be interesting to see if there is something in it

DAM NICE WORK!

Grim

 

[Joern Markset]

It has been quit a long time since I have shared any news. While the water is solid I will try to have a .12 tunnel finished for testing next year.
It will be powered by OS Speed T1203 in a gearbox setup. OS 18TZ will be an option.

 

[Kris Flynn]

What hull will you use for a .12? On an OS lower?

Those gear drives look VERY nice!

Did you ever try a small carby (10mm) on the Nova 46? That reduced the noise ALOT on my outboard, would give good bottom end also. With some tuning it could work well for you IMO