blackbird345

Has anyone tried these props on a 31ft American Offshore? My hull is a '98 and Ive been told that the Lightning are great props for this hull, anyone have any experience? I have twin Mercury 300x motors and the props are 24P. Grateful for any feedback.

STV92

Im running 28 choppers on mine & love them.
But Im running 3 225 promax.

We are few outboards
How does the 2 300x run?

I am hoping to upgrade to 300xs x3, thats my future,
Now I just need to sell the wife,,,

blackbird345

Hahaha nice! I'm only getting mid 60s out of my boat now because I can' only jack up the left engine a little before it overheats and goes into guardian mode. I think its the exhaust gasket/seal leaking into the water pressure. The last guy that had it got 78 mph out of it but that's with 21 Bravos. What year is your boat? Wish I could run 28s, that'd be awesome but need more torque. What kind of top speed are you getting again?

STV92

no way was the last guys running 78mph with 21 pitch props.

I am turning 6800rpms with the 3 promax's.
Im running between 75-80 mph.

Mine is a 1996 Awesomecat,

with 2-300x motors you should be running faster.
I run low water pick-up and transom pick-ups for the 2 outside motors.

They are very heavy boats & need alot of torque to run numbers.

You need more then just low water pick-up to help cool the motors.
Sounds like your are low in the water

Send me some pics of the transom & motors so I have an idea of your set-up.
[email protected]

They are great boats in rough water, but you will need the rough water to pack air.
Calm waters, its like the boat is glued to the water.

blackbird345

I assumed the 78 was with the 21s but maybe not. The engines are way too low but when I go to lift left engine it alarms. I can raise right engine w no trouble.

I cracked the blades on one of the 21 bravos so I borrowed a prop which happens to be a 24 p lightning. So left engine still on 21 bravo right on lightning 24. Yes I know its weird and not a good practice its just temporary, but its amazing the difference in how the boat feels! The boat feels way lighter even w just one lightning on. It really feels like its raising the transom like they are suppose to. Can't wait for both lithtnings that I just purchased from Mike at Halls Propeller to arrive! Just gotta get left engine cooling sorted out and should be good to go. My boat isn't on a trailer yet because it stays in canal. Hoping to pull it out tomorrow and I'll take pics.

STV92

Do you have low water pick-up?
Do you also have transom or bottom pick-ups?

Does the alarm go off when your running or when you try to go on plan?

When the alarm goes off, what water pressure do you have?

With the engines low in the water you should have great water pressure, but alot of drag in the water.

Good luck,,,

blackbird345

I have Bob's nose cones w low water pickups on both engines, but don't have transom or bottom pickups. My best water pressure on the left engine is around 7psi. and it runs warm on that, i can only jack it up a little bit before it starts losing pressure, anything below 7psi it alarms and goes into guardian mode.

I can't get top end out of it till I fix the left engine and the alarming bc its just way too much drag. The right engine stays at 10psi even after jacking it up a bit.

STV92

7-10psi is not enough, even 10psi thats low.

Stupid question but have you checked your water pumps?
with the engines low in the water, you should be running over 10psi.

IS YOUR NOSE CONE EVEN WITH THE BOTTOM OR MUCH LOWER?

I run 10-15 psi & running clean, it will run up to 15-18.
But again, I also run transom pick-ups & lwpu.

Do you have set back & if so how many inches?

Pics would really help to understand.

blackbird345

So this is a weird question, but can I have a transom mount water pickup that runs to where you would normally flush the engine with a hose? Would that not give enough water?

BTW, I got 66.9 mph with the 24p and the 21p. But I realized the 21p was at 7200rpms doing that and backed off immediately. Thats the fastest I've got so far...I know its not impressive but gives me hope with the new props when they come.

jpearce

I have a 1991 31' with two 300x motors with 15 x 28 props & on GPS I have hit 84 mph but my boat has no lift unless it is rough I am looking to change my props from a three blade to a four blade prop but not sure what pitch to run.