prop question

[quad59]

Ok I think I need alittle more prop. I looked and I couldnt find a number on mine but here is whats going on. The manual for my motor a 1984 90 hp yamaha 2 stroke says that the rpm range is between 1k and 5200. When I am running full out my motor will turn 6100 on the rpm gauge with no real increase in speed after 5k. Also when I holeshot as the nose is coming down the motor overrevs and for a brief second its almost like it stops pulling. I have a 16.5 ft glastron ssv-167 its a 1981 vhull. Boat and motor with a tank of gas is about 1500 lbs. Do you guys think I need more prop??

 

[Dhadley]

Re: prop question

You might indeed need more bite but we also need to know the condition of the existing prop. It may well have been the right one and just worn a bunch. At any rate we need to know it's condition and size. The make and model would help too. We'll assume it's a 3 blade but is it ss or aluminum?

 

[quad59]

Re: prop question

it is a 3 blade aluminum and seems pretty well used. I tried to locate a size on the outside but didnt see one. I will have to remove it and look at it closer. By well used I mean there are a quite a few nicks and scrapes on it.

 

[Dhadley]

Re: prop question

OK, good info. Let's see what the numbers are and go from there.

 

[Sandhammaren05]

Re: prop question

Is the trailing edge cupped? Probably not. If not, get it cupped out to maximum radius. If already cupped, get more cup out to maximum radius

Ok I think I need alittle more prop. I looked and I couldnt find a number on mine but here is whats going on. The manual for my motor a 1984 90 hp yamaha 2 stroke says that the rpm range is between 1k and 5200. When I am running full out my motor will turn 6100 on the rpm gauge with no real increase in speed after 5k. Also when I holeshot as the nose is coming down the motor overrevs and for a brief second its almost like it stops pulling. I have a 16.5 ft glastron ssv-167 its a 1981 vhull. Boat and motor with a tank of gas is about 1500 lbs. Do you guys think I need more prop??

 

[quad59]

Re: prop question

The only number I found on the prop says 17-k. There is not alot of room between the tip of the blade and the top of the lower unit. I would say maybe 3/8 of an inch.

As to the cupping question the trailing edge of the hub flares out alittle. The leading edgs is flush with the unit housing but flares out on the trailing end

 

[Dhadley]

Re: prop question

OK, that's a 17 pitch. I thought the K series was ss but if yours is aluminum that's what we'll go by. If it's worn as much as you say that would explain all the slip therefore we don't have a lot to go on as far as real world numbers go. However, 17 would seem like a good pitch for that combo. Especially if you go to ss.

 

[quad59]

Re: prop question

So your recomendations are to get a new 17 pitch ss prop? Thanks for all your guys help.

 

[Sandhammaren05]

Re: prop question

Go to a prop shop, or send the prop to a good shop (Bauman in houston, hill in Calif., ...) and tell them to cup the trailing edge of the blades out to max. dia. Trailing edge of hub is something different! You could send it to me but I'm out of the country til Aug. Good luck.

The only number I found on the prop says 17-k. There is not alot of room between the tip of the blade and the top of the lower unit. I would say maybe 3/8 of an inch.

As to the cupping question the trailing edge of the hub flares out alittle. The leading edgs is flush with the unit housing but flares out on the trailing end

 

[Dhadley]

Re: prop question

Yes, I would think that a 17 would be a good choice. Something like the Stiletto that's made for your application. Personally I wouldn't sink a lot of money in an aluminum prop that's well worn now. I'd put that money toward a decent ss prop that will be with you for quite a while. If you have trouble finding what you want just let me know. I'm sure we can come up with some ideas.

 

[quad59]

Re: prop question

I ordered the prop today. I got a 17 alluminum. I didnt want to get anything fancy as this is just a testing boat and I dont want to sink to much money into it. If the family has a good time this year the street bike goes next spring as well as this boat and we going to go to like a 20'. After lots of reading today I did however order some smart tabs to try out so I am excited to see what the new prop and tabs will do. My boat is shaped kinda funny in the reat though so I think mounting them will be a challenge. Thats for another thread though. Thanks for all your help and I'll let you know how it all works out in a week or two.