another, prob dumb, prop question Honda 50

[taime1]

I too was thinking about re-proppoing. I have a 4-blade singing prop which is really annoying, but runs ok. I also have a 50 Honda and can get about 12-13 knots out of if, ballast out, bottom paint on and mast up.

I was thinking og oing to a composite, probably from Pirahna props. You can change out the blades if you want to change the pitch. This is their website: http://piranha.com/

They have a prop finder tool, which will lead you to the HC3 hub and its choices. I think I would go for the 12 inch diameter with either the 9 or 11 pitch. There may also be an older post on them.

Not sure if anyone active has been using and can report on them, but I like the concept.

[NiceAft]

They have a prop finder tool, which will lead you to the HC3 hub and its choices. I think I would go for the 12 inch diameter with either the 9 or 11 pitch. There may also be an older post on them.

Interesting, I also decided on a prop of those dimentions. I just have not figured out from where.

Ray

[Whipsyjac]

Theoretically the difference is two miles per hour.

The first one has a slightly smaller diameter to give you enough torque advantage to turn a faster(higher number pitch)

The second one will move more water with its larger blade area but this takes more torque so they lower the pitch.

More diameter or more blades move more water and slip less.

The theoretical short cut is to double the pitch( the last two numbers of a prop's designation) and it gives you your boat speed in miles per hour. This is based on an average slip of twenty percent and a two to one gear ratio. My best prop, which I just got this spring, slips around thirty percent but my worst prop is close to fifty percent slip.
Example: A nine pitch prop gives a theoretical eighteen miles per hour, a ten pitch prop gives twenty miles per hour. Of course the theory is only theory and in the real world my new twelve and a quarter inch diameter prop with a nine inch pitch is giving me sixteen and a half miles per hour in an empty boat.

I've got a noticeable difference with my large area/diameter three- blade over my slightly smaller diameter four- blade. Namely the four-blade was actually seven hundred rpm under the WOT minimum RPM and the three- blade gives me a mile and a half better top speed at the top recommended RPM so the motor is running free and easy.

I checked and the prop manufacturer recommends the same props for you even though you have a lower gear ratio. These are cheap props from Michigan Wheel with an exchangeable hub system so trying new ones is less expensive. I got mine from Tacomapropellor

Since you have a lower gear ratio I would definitely try a ten inch pitch minimum in a three blade. If you are lightly loaded an eleven inch pitch should/could work.

Here's the three blade, note you also need a hub kit. These props will also work with mercury exchangeable hub props and turning point exchangeable hub props.
http://tacomapropeller.com/propellers/d ... ductID=178

Here's the four blade
http://tacomapropeller.com/search-resul ... ductID=194

Do your best to find out what pitch you are running now and make a decision based on that.

I hope this helps,
Willy

ps...spelling out numbers helps right?

[NiceAft]

I am not at the boat at this moment, but I believe I currently have an 11 3/4 x 10. I am moving up a little in diameter and shrinking the pitch to a 9.

Ray

[81venture]

ps...spelling out numbers helps right?

Actually, No unfortunately, it makes it worse. Have to read the numbers (yes reading them helps in that respect) but then in my head have to try and convert that into actual numbers etc....once again that part of my brain just "shuts down" and I get confused.

But the theory of course makes perfect sense.

I guess I am just going to pull off the one that is on there, read the #'s on the back of the prop and just order another one...it worked good enough, the boat moves.

[Catigale]

What song does your prop sing? Taylor Swift Boat?

[Tomfoolery]

What song does your prop sing? Taylor Swift Boat?

I think it's more like a hum. Probably doesn't know the words. It sounds a bit like the Colonel Bogey March to me, but I don't know the words, either, so it's ok.

[81venture]

I've been real busy with the 26x...been a four day project so far

Pulled EVERY wire out of it...doing a complete re-wire from bow to stern, and cabin

Anyway I pulled my prop off to see

It is an 11 X 3/4 X 10


Dave

[81venture]

Theoretically the difference is two miles per hour.

The first one has a slightly smaller diameter to give you enough torque advantage to turn a faster(higher number pitch)

The second one will move more water with its larger blade area but this takes more torque so they lower the pitch.

More diameter or more blades move more water and slip less.

The theoretical short cut is to double the pitch( the last two numbers of a prop's designation) and it gives you your boat speed in miles per hour. This is based on an average slip of twenty percent and a two to one gear ratio. My best prop, which I just got this spring, slips around thirty percent but my worst prop is close to fifty percent slip.
Example: A nine pitch prop gives a theoretical eighteen miles per hour, a ten pitch prop gives twenty miles per hour. Of course the theory is only theory and in the real world my new twelve and a quarter inch diameter prop with a nine inch pitch is giving me sixteen and a half miles per hour in an empty boat.

I've got a noticeable difference with my large area/diameter three- blade over my slightly smaller diameter four- blade. Namely the four-blade was actually seven hundred rpm under the WOT minimum RPM and the three- blade gives me a mile and a half better top speed at the top recommended RPM so the motor is running free and easy.

I checked and the prop manufacturer recommends the same props for you even though you have a lower gear ratio. These are cheap props from Michigan Wheel with an exchangeable hub system so trying new ones is less expensive. I got mine from Tacomapropellor

Since you have a lower gear ratio I would definitely try a ten inch pitch minimum in a three blade. If you are lightly loaded an eleven inch pitch should/could work.

Here's the three blade, note you also need a hub kit. These props will also work with mercury exchangeable hub props and turning point exchangeable hub props.
http://tacomapropeller.com/propellers/d ... ductID=178

Here's the four blade
http://tacomapropeller.com/search-resul ... ductID=194

Do your best to find out what pitch you are running now and make a decision based on that.

I hope this helps,
Willy

ps...spelling out numbers helps right?

I just went ahead and ordered the one you posted.... gotta start somewhere

Be here in 5-6 days

[Catigale]

What song does your prop sing? Taylor Swift Boat?

I think it's more like a hum. Probably doesn't know the words. It sounds a bit like the Colonel Bogey March to me, but I don't know the words, either, so it's ok.

I'm just gonna wake wake wake wake....wake it out...

[taime1]

I am moving up a little in diameter and shrinking the pitch to a 9.

I just did this very change. I have a Honda 50 and went from my four blade (not sure of the size and pitch) and put on a MW 12¼ X 9. Did my first run last night and was very happy with the non-singing. There was some wind maybe 8kts and I'm sailing in a river which has about a knot or half knot of current, but upstream and into wind I was able to get up to 13.8kts with no ballast (do have bottom paint). Downwind and with current, I hit about 14.7kts, probably would have gotten better, but I also wanted to get some sailing in, so I didn't motor around very long.

I was also able to get in some pretty sharp turns, mush sharper than with the 4-blade, which got unhappy in relatively soft turns. I did get a little spun out running at top speed and turning nearly as sharp as the boat would allow.

At WOT and no ballast, it spins just beyond the recommended upper RPM limit (a touch over 6000). I think ballast in kept me at or just below 6000. So I think the prop is pretty good and seems to be the right size. It would be fun to try a pitch of 10 or 11 to compare, but I think the 9 is pretty good.

[Starscream]

I have a composite Piranha prop that I keep disassembled down below as a spare.

It's not a great prop, in my opinion. The idea makes sense and they do a good job marketing it, but for me it doesn't perform as well as a same-size aluminum prop. I forget the actual numbers, but with the E-tec 90 pushing hard I max out at 4800 RPM and 20mph fully ballasted with an aluminum prop. With the Piranha the RPMs jumped to something like 5500 RPM, from memory, and I was down to about 17 or 18mph. Could be due to prop flex under load, but who really knows? Maybe the Piranha wouldn't have the same issue with a 50 HP?

I wouldn't buy it for a primary prop, but it stores very nice in small, light pieces as a backup.

When I had the BF50 I put a 4-blade Honda prop on and was quite happy with it, getting 8 mph ballasted and 16 or 17 unballasted. No singing. I forget the actual pitch and diameter but I can look it up for you if you like.

[81venture]

When I had the BF50 I put a 4-blade Honda prop on and was quite happy with it, getting 8 mph ballasted and 16 or 17 unballasted. No singing. I forget the actual pitch and diameter but I can look it up for you if you like.

I had to search and find this thread, hoping the links to the Tacoma propellor were here and worked... they are, but don't go to the product

I am re-visiting the Idea of going to the 4 blade....

Any chance you could get those #'s still starscream?

[Starscream]

Yes it was an 11.8x9 four blade prop bought directly from a Honda dealer. I was happy with it for the BF50A. I could hit 16 mph unballasted.

[opie]

Before you buy a 4 blade prop. google the following terms:

4 blade singing prop