Alpha 1 gen 1 with v8

[Jakem]

I have been told I should put a smaller prop on my boat wich is a 23 foot campion cruiser fiberglass. It has a 19 on it now. I am putting in a new 302 and want to match prop. It was suggested a 16 or 17. Any input would help

 

[Scott06]

I have been told I should put a smaller prop on my boat wich is a 23 foot campion cruiser fiberglass. It has a 19 on it now. I am putting in a new 302 and want to match prop. It was suggested a 16 or 17. Any input would help

Were you able to run it with old engine and see what the performance was?
Was it getting the engine to recommended WOT rpm range?

Without a basis point of what RPM range at WOT its hard to say, as long as the 19" is in good shape I would trial that then make an educated decision.
Depending on what gear ratio is in the drive I would think somewhere between a 17- 19" is where you would land, 15 or 16" if you have a lower gear ratio or go with a 4 blade.

 

[Jakem]

No I didnt really get a good run after I switched it from the 21. That's when it all started to fall apart.

 

[Scott06]

No I didnt really get a good run after I switched it from the 21. That's when it all started to fall apart.

Ok so get it back together put the 19” on get it tuned right then check the rpms. Not sure what the wot range is for that engine but guessing 4400-4800, 5 k at most.

 

[Jakem]

When I first got the boat wot was about maxed at 3500

 

[Scott06]

When I first got the boat wot was about maxed at 3500

if the tach was accurate, the was not waterlogged, and the engine was in good shape and tuned up, then drop 4" in pitch....but I assume the engine was not in good shape since you just replaced it right?

 

[Jakem]

I'm replacing it yes...won't be ready till March. It was definitely not healthy

 

[Scott06]

I'm replacing it yes...won't be ready till March. It was definitely not healthy

If it were me I would run what I have to get the baseline established then you can tweak it from there.

Usually 19" is a good starting point. Unless someone has changed the drive ratio typically they are geared by the boat builder such that 17"-21" props (power to cruise) will work.

 

[Jakem]

Gotcha. That's what I will do