Bobs nose cone or ???

[Joakim]

I have plans for a bobs big nose cone.

A friend told me i will lose speed because it is longer wet area in the water

And it is mostly for catamaran hulls...

Right or wrong...?

Anyone here done this? difference before and after big nose cone?

Or shall i go for a transom waterpickup...

[Jay Smith]

I'd have to disagree with your friend....

All the fastest V bottom boats as well as tunnels here in the states run extended cones.. ALL OF THEM !!!!!

I've had GREAT luck with Bob's cones..

Jay @ JSRE

[RossM]

Originally Posted by Joakim

I have plans for a bobs big nose cone.

A friend told me i will lose speed because it is longer wet area in the water

And it is mostly for catamaran hulls...

Right or wrong...?

Anyone here done this? difference before and after big nose cone?

Or shall i go for a transom waterpickup...

A nose cone gearbox would actually be slower if the boat runs aound 70-75mph, if you have a setup which would do 80+mph then you need a low water pickup / nose cone

[Tony Davis]

Originally Posted by PuppiesBalls

A nose cone gearbox would actually be slower if the boat runs aound 70-75mph,

Why??

[RossM]

Originally Posted by Tony Davis

Why??

dont know dude, I googled it and thats the answer i found....could be because theres more surface area & so more drag, maybe because a rounded nose of the gearbox is more hydro-dynamic (think rounded tip of aeroplane wing)

[Joakim]

I understand that the waterflow will be little different with a longer house.

And can see how many fast monos use bobs nose cone or simular on their boats.

The rope on the pics is inline from the step true the transom.

Full down and 4" up on the pics.

[Cookee]

Originally Posted by PuppiesBalls

dont know dude, I googled it and thats the answer i found....could be because theres more surface area & so more drag, maybe because a rounded nose of the gearbox is more hydro-dynamic (think rounded tip of aeroplane wing)

Ah Google! Why not leave it to someone who actually knows the answer!

On our old raceboat we ran from 70mph to over 90mph with different power and the handling was always better with a nosecone on a Sportmaster with no loss of performance that we could detect. The added benefit is better water intake and you can raise the motor and reduce drag which improves performance.

Edit: You could always ask Adam Younger who designed the boat in the first place?

[Joakim]

Originally Posted by Cookee

Ah Google! Why not leave it to someone who actually knows the answer!

On our old raceboat we ran from 70mph to over 90mph with different power and the handling was always better with a nosecone on a Sportmaster with no loss of performance that we could detect. The added benefit is better water intake and you can raise the motor and reduce drag which improves performance.

Edit: You could always ask Adam Younger who designed the boat in the first place?

Thanks Cookee.

It was Adams suggestion from the beginning. The set up today is amazing, but i am new to boats with a lifter so i do not have the feeling in my fingertips yet.
Because of that i would like to be safe atleast with the cooling.

So this means a transom water pick up is not the right way to go.

[Adam]

For me nose cone kits are generally of benefit when running high shaft heights with standard gearboxes - failry obvious really.

Onto speed and stability - they really work on boats where you are running neutral trim, thus keeping a failry constant frontal area to the waterflow. Certainly not increasing the frontal area over a standard box.

However with lots of trim (in or out) the extra length is increasing the effective frontal area to waterflow and this can cause more drag.

As with all changes it is often part of a bigger picture and by going to a nose cone you might be able to change your prop to some extent, run higher etc.

[Joakim]

Originally Posted by Adam

For me nose cone kits are generally of benefit when running high shaft heights with standard gearboxes - failry obvious really.

Onto speed and stability - they really work on boats where you are running neutral trim, thus keeping a failry constant frontal area to the waterflow. Certainly not increasing the frontal area over a standard box.

However with lots of trim (in or out) the extra length is increasing the effective frontal area to waterflow and this can cause more drag.

As with all changes it is often part of a bigger picture and by going to a nose cone you might be able to change your prop to some extent, run higher etc.

Thanks.

Do i need to weld the nosecone to the gearbox? I have seen both welded and plastic expoxy....

[Scand]

How fast are you running at the moment?

[Joakim]

Originally Posted by Scand

How fast are you running at the moment?

With engine fully down 50,5-51 knots.

Up 2" 53 knot... at 5350 rpm

Up 4" not tested

56 is done in Uk.

With a 24" Raker

Short test with a Hydro 24" 4 blade felt very good. But i could not do the full speed test. But much faster up to 46-48 knot.

[Adam]

Yes, saw 64 mph (56 knots) in the UK - but had to go pretty high and she was quite loose. It was also without the A-Frame being fitted and running quite light.

That was with the modifed Raker - but there was always more props to try......

[Scand]

As the torpedo on your outboard is quite sharp, an easier option would be to use a transom mounted water pickup.

[Joakim]

Originally Posted by Scand

As the torpedo on your outboard is quite sharp, an easier option would be to use a transom mounted water pickup.

That is one option.

Have not seen any pics on a boat/engine with a transom mounted pickup.

I never tilt the engine all the way, just adjustments for driving so maybe

[Techteam]

Originally Posted by Joakim

Thanks.

Do i need to weld the nosecone to the gearbox? I have seen both welded and plastic expoxy....

I would always weld as its very difficult to get good alignment with the epoxy taking so long to go off and you can make a gearcase very slow with bad alignment. I tend to make very small tacks constantly checking the alignment to make sure it's not pulling out of line. I then do 20mm runs with a lot of time in between to not build too much heat in the case. Use the epoxy for the first rough fairing and then Chemical Metal for cosmetic fairing and finishing before paint. Shouldn't get any cracks appearing.

[Bokito]

Use the epoxy glue, hand machine it as long as it will be sucked at the gearbox, so a clean fit will take you some patience.

Wouldnt weld on the gearcase.
Only skeg and cav plates should be welded and if only by those who do a lot of skegs.

An idiot will ruin your gearcase forever welding it.

I run a low water pick up, it will take water for ever, when you have an hydaulic lift take the nose cone, best waranty for water pressure.

[FrenchPhil]

If your already running a CLE/Sportmaster I'd keep it as it is & try more height & prop combos. If you want to try & to get the last few mph then get a hydro jackplate & transom water pickup.

What's your engine?

[still no worries]

Phantom 18 xr2 cle 1mph faster than sportsmaster
(after lots of testing, we had 2 cle's 1:87 and 2:1 and 2 sportmasters 1:87-2:1)
If that's any help.

[Foolish]

Originally Posted by Techteam

I would always weld as its very difficult to get good alignment with the epoxy taking so long to go off and you can make a gearcase very slow with bad alignment. I tend to make very small tacks constantly checking the alignment to make sure it's not pulling out of line. I then do 20mm runs with a lot of time in between to not build too much heat in the case. Use the epoxy for the first rough fairing and then Chemical Metal for cosmetic fairing and finishing before paint. Shouldn't get any cracks appearing.

we tried just using the supplied epoxy the first time but cracks started to appear after a couple of races so stripped it all off and refitted with 6 30mm welds, also finished with chemical metal, three years on had no further problems