motors on pods

[Black_Jack]

HI

What height would you bolt on a motor onto a pod? Is their any maths to it?

boat is 6m and the pod is 0.7m



geoff

[blaze]

rule of thumb is an inch up for every foot back so somewhere around 2"
cheers
blaze
ps
I dont like pods

[Ron173]

Geoff,

I've not had a pod yet, but unless its hugely different, wouldnt you want your cavitation plate level with or just under bottom of hull?

Ron

[blaze]

Hi Ron
If its a hull extension the standard mounting practices are used.
If its a pod that dosnt go to the water line (may sit 300mm above water line) then it needs to be above the hull because as the water is displaced out the rear of the boat it rises.
Hope that clears it up some
cheers
blaze

[Black_Jack]

blaze,
if your motor is to low on the pod, will it cause the back to dig in?

attached is a sketch of the rule of thumb.


geoff

[blaze]

Hi Geoff
As I said previously I dont like pods and the reason being that they create an uncertain outcome, boats designed to have pods have them. Engineers and builders spend millions of dollars designing and testing new ideas before they go on the market.
One thing for certain is that if the leg is to low it will create drag and too high it will cavitate.
The sketch in my view is in the ball park but you will need to fine tune it after test runs.
Hope all works out for you
cheers
blaze

[MulletMan]

Agree with Blaze, have seen too many boats come to grief after fitting a pod.
When done by the manufacturers and engineers, usually OK, but still would be real careful about "modding" a boat that wasn't designed to carry one all the same!

[FNQCairns]

"if your motor is to low on the pod, will it cause the back to dig in?"

No it will do nothing but create extra drag, this extra drag the prop will need to overcome and will increase fuel consumption and decrease speed for RPM, acceleration, handling and may also increase porpoising as it's main cause is prop slip and the resultant decrease in bow lift.
Thenumbers on your sketch look fine and then everything Blaze said.

cheers fnq

[Black_Jack]

Thanks Guys,

The boat is factory fitted with the pod, i seem to get alot of bow lift when i take off. I use trim tabs to over come that but i feel as if the motor sits low. I will measure the height of the motor to the boat.

Let u know how i go

thanks

geoff

[FNQCairns]

Geoff the inch up for every foot back is simply a rule of thumb if you think it is too low it probably is, most fishing boats I see have engines low enough to to be a ski boat. Being a fishing boat the setup is bias toward cruiseing speed handling and economy, some have a real need for low engines like being constantly in very rough seas (cray fishers near rocks, blaze) or always crossing bars but most people dont do this sort of stuff often.
Anyway if when at cruise and above if you hook the boat into a turn a bit like you were tubing with your kids but not mega dramatic and the boat stays fully hooked up (doesn't cavitate at all) you want just a hint of cavitation, the engine is probably too low for efficient running-well worth trying a hole or so higher to see anyway.

The bow lift I mentioned above is bow lift from planing speeds to flatout not when the bow comes up under acceleration to get onto the plane, to deal with that good use of engine trim and trim tabs is needed.

cheers fnq