what size prop

[buzzyb]

i have an 18ft lund alaskan with a 2006 yamaha 50hp 2-stroke
and i am looking for a prop that will be a good all around prop.
sometimes i run mt and sometimes i have a good load[200- 300lbs] maybe more. i have a 10 5/8 x 12 right now but i does not seem to reach full rpms.
thanks

[almetelo]

"does not seem to reach full rpms"

Do you have a tach?

[buzzyb]

no do not have a tach

[robert graham]

An 18' Lund with a 50HP might seem a bit underpowered...maybe it's doin' all it can?...without a tachometer of some sort it'll be hard to tell...unless it used to run a lot stronger before and has recently run weak, indicating a problem with the motor?

[almetelo]

looks like 50HP it minimum recomended by manufacturer.

Like Graham said is difcult to pick a prop without a tach.

1st you need to get a tach, then learn (or not) a little about props.

Choose a prop acording type of hull, fuel weight, number of persons usually on board etc etc even temperature and altitude affects performance of motor and choise of the props.
In my case I had the luck to have someone that loaned me props to test on my boat/motor (5) untill make sure that was the right prop.

I like this site:

Boat Propeller Advice & Tips

but for sure many others with lots of informations.

[buzzyb]

its an older alaskan the tag in the boat says max engine is 60hp

[YammyMan]

You should try a 14 or 16 pitch. That will give you a little more top end and a little less take off.

[buzzyb]

what about diameter how much differance does that make
thanks