Prop selection for 5hp dinghy

[brsoo]

I just purchased a 8.6' inflatable dinghy that weighs about 80lbs . the motor is a 96 nissan 5hp 2stroke. Ns5b
The current prop seems to be original aluminum 7.8 x 7.8 haven't ran it but it is dented, bent, and worn out from sand.
Does this motor take a 8 or 12 spline? I can not find the correct info online.

I have found three choices online I might try. If I have the spline right. All are aluminum
1. 8" pitch
2. 7.5" pitch
3. 6" pitch

I'm likely to not exceed 500lbs total weight on the boat. Id like good top speed and decent acceleration. From my understanding slightly less pitch is best.
What do y'all recommend? I might buy two of them to try

 

[jimmbo]

As always, if a selection of props are available, you need a baseline to work from. What is your current WOT rpm, and what is the WOT rpm range?

 

[Scott Danforth]

I would pull your prop, look at the spline issue yourself and get the 7.5"

 

[Sea Rider]

Whichever prop you choose won't be able to plane out that small inflatable with a underpowered OB, hull drags awfully due to its size. Only good for fast boring displacement speeds.

Went through the same scenario myself with same 5 HP-OB. Current factory delivered prop was a 8 pitch and was impossible to plane out a much larger 13" inflatable while solo boating, swapped for a 7 pitch and plane beautifully at full throttle and maintained plane at 3/4.

Before investing blindly on a new prop, remove prop and count the splines on the prop shaft, should be 12 splines, as found on newer year 5 HP-Ob's. Once it's known report back.

Happy Boating