Propeller question

[kenny nunez]

My Donzi has a 14-1/4” X 22” stainless propeller that works perfectly. The only place the pitch is embossed is on the front under the thrust collar. I was trying to figure what series the propeller is. The boat runs 70 @ 5000 on GPS.

 

[alldodge]

Most Alpha/Bravo 3-blade props have an odd ratio pitch (19, 21, 23, etc). Don't know about the series but assuming it has a 1.5 drive and tach is accurate, the 22 cannot be right because it shows a neg prop slip. If its a 23 that would be great and still a bit unreal at 3.6%

http://bblades.com/propeller-slip-calculator/

 

[kenny nunez]

The speedometer stops reading @ 65 because the pitot is too far from center. The guy I bought the boat from 2 years ago said it would go 70, I was skeptical. I have rebuilt the transom and re-routed the exhaust through the drive. Now you can hold a conversation @ 30 without screaming. Now I have to sell it because my wife is afraid of it. The engine and SE drive only have 45 hours showing on the Rinda.
I understand that 80 model 2+3s were known as a “light layup” hull. When I cut through the bottom for the water pick up it was just over 3/8” thick.

 

[alldodge]

Bummer with having to sell a fast boat. I'm sure its doing 70, just wondering about the prop pitch and/or tach accuracy

 

[QBhoy]

Hi
no doubt its a fast boat. No doubt at all...but it’s maybe not doing 70 gps in reality. My boat...god knows I’ve tried everything..just will not get to 70. It’s like a brick wall barrier that most boats won’t see past. I only have about 10-20hp less than you and I’m an 18ft flat pad apex hull. I’ve tried about 6 props to date. It won’t go by 66.7mph gps and usually won’t see past 63/64 most times on average.
Even at its best it will have a prop slip of just under 4%...at its absolute best and perfect conditions.
Your 22” is likely either a 4 blade or one of mercs special props like a enertia or similar. Mostly come in odd sizes for these.

 

[QBhoy]

Ps. Just to further explain the difference between gps and speedo (dreamometer) speed...at anything over 63 mph GPs...my boats speedo will read off the clock at the 70 mph increment. Wildly not accurate

 

[QBhoy]

 

[kenny nunez]

I am sure about the propeller, it appears to have never been worked on. I cannot find anything on it other than the diameter -pitch # on the front under the thrust collar.
My brother In law’s BPM was 100 when we were running the boat on his GPs watch. There is a wide outfall canal 4 mlles from the launch which is a perfect place to test. One of my friends hit 140 in a 30’ Poker run boat in that canal.
If you google map Kenner,La it is at the west side running N-S into the south side of Lake Pontchatrain from I-10.
If anyone is interested in the Donzi I can send pictures.

 

[alldodge]

If anyone is interested in the Donzi I can send pictures.

Be careful Kenny the rules

 

[QBhoy]

Hopefully you don’t think me critical. Just trying to offer some real world advice.
Regardless of all that. What a boat a donzi is at any speed.
Always wanted a classic 22. Very hard to come by here in the U.K. though. So envious of you guys and the options on boats you have there.
Mine of my boats came from Canada and is the only one like it in the U.K. so lucky so get that but there are plenty others that are widely available cheap to you guys and not to me.
The hydrostream is a prime example.

 

[QBhoy]

Sorry for going on again...and you likely know already...but just go easy with that thing you have. The alpha will be at or beyond it’s limit of comfort with the 6.2 mpi. Wind the power on easy I’d say. I do the same.
Just remebered that there is a hydralift boat here on the lake with a 6.2 and alpha one. He can get 66 mph gps when conditions allow, so you won’t be too far off that in the donzi I’d say.

 

[Faztbullet]

Your propped really close so leave it alone if you selling it. If prop is a lil rough have it dressed up. On high perf hulls the X height is higher than a your standard runabout . Just helped a buddy on his Baja drive conversion to XR's as the Bravos are to weak. 32 pitch props jumped a wave at 80+mph.... splines gave up when prop loaded back up.