3 blade props with outboards...

[Drmeff]

I am new to outboards, and I just ordered a prop for my new boat that is coming to me and realized I ordered the x440/3 (it was a great prop for my catamaran!) and I am wondering if this will work out alright on an outboard? I also have a slightly modded x440/2 that I could use instead if I had to. So are three blade props alright for tunnels?

 

[jetpack]

The difference I've noticed is the hull experiences a little bit more of propwalk at high speed, and you will get more turning ability in the corner, but will lag a little out of a corner if you back off. Top end seems better. On my KB SS stock it was definetly a fan blade with that size and blade number. My X437/3 seemed to have better characteristics, but not as fast down the chute. The X440/3 was about the biggest prop I would want put on it without modding, and trim changes became very critical. Three blades will load a motor more at anything less than full step, but definetly add top end speed. That has been my testing experience. After trying all my trim changes, weights and balances, I decided it would be best to drop back down and ran my X437/3 consistently and decided the X440/3 would be a good one to experiment with reshaping. If I wasn't concerned about wild rides through the corner and wanted pure top end ability...the X440/3 is the dealie.

 

[Duck899]

I run a stock X-440/3 on my stock K&B 3.5 SS powered Leecraft.....Its the fastest 3.5 tunnel I've driven for the last 5 years.....And, I'm talking 6 lap race course times....corners like its on rails.....

 

[jetpack]

BTW, my hull I was testing with was an ABS Sprint, not as much deadrise as the Lee and I bet this is why I had tripping issues in a fast corner. With that hull I bet that prop DOES do a excellent job!

 

[Drmeff]

Ok, sounds like I will have some experimenting to do with it! At least I know that it is ok to put one on there! I have just been hearing pretty much exclusively about 2 blade props and I thought that 3's may not agree with this style of boat at all, but that doesnt seem to be the case! I guess I will keep the 440/3 and see how it does, if it is too much I will back off to the x437/3 or x440/2. I have also heard a ton of good things about modded 1440's so I have some props to put on my wish list!

 

[topfuel443]

You didnt say what hull and motor you have, but I like three blades because they tend to calm down a tunnel quite a bit. The X440/3 in stock form, is a bit large for most 3.5 outboards, it will be much better, detounged, and backcut. I like to round the tips a bit to take it down to about 38.5-39.0mm diameter. The "sport" or non pipe motors may benefit from it a little more than a piped motor as they tend to have more torque, and not rely so much on RPM. I think a cupped up 437/3 is the ticket on many set-ups. The X442 is also a good prop with a little work.

~James

 

[chuck]

I've been running the X537/3 on most of my tunnels. It has the same pitch as X440/3 but smaller diameter. Stock 437/3

has 2.07 pitch and the X537/3 has 2.20 pitch. My 2 cents.

 

[Drmeff]

I will be taking the tongue out of the 440, and I will definitely experiment with some back cutting.

It will be going on the boat I bought on these forums from Adam (watercadet) which is a JD WOF 28 with a K&B 3.5ss Gold carb.

Thanks for all the tips, this should keep me busy between race dates!