prop advise please i/o

[schlosser1]

i have an 84 diplomat i just put a 350 in i am running a slightly beat up 21p solid hub cleaver prop. 61mph on speedo at 4400 comes out of the hole pretty good i would like to try a 23p but am now confused as of what to look for diameter and model mirage,trophy,vengeance, and so on i need more bow lift and a little less diameter i think. any suggestions guys?????

 

[schlosser1]

found a 23p 14.25 vengeance prop for 150 should i buy it someone said the vengeance isn't a performance prop????

 

[RLCBoats]

i have an 84 diplomat i just put a 350 in i am running a slightly beat up 21p solid hub cleaver prop. 61mph on speedo at 4400 comes out of the hole pretty good i would like to try a 23p but am now confused as of what to look for diameter and model mirage,trophy,vengeance, and so on i need more bow lift and a little less diameter i think. any suggestions guys?????

We have tested 2 diplomats and found that a 22 pitch 4 blade Hydramotive quade 4 OT prop worked the best on that boat.

 

[schlosser1]

was that an i/o or outboard?

 

[wca_tim]

my 88 diplomat does the best with stern lifting props with a stock length drive on it - especially at higher speeds. I'm assuming based on your numbers that you're running a 1.5 gear outdrive. you need less pitch, not more. probably as low as a 19. you want to get your rpms up a good bit. a lot depends on the engine... what is it?

I'd also dare say that a quad iv is WAY too much prop for that boat. That's a 15 - 15 1/2 inch prop.

your best bet / fastest is probably going to be something along the lines of a laser 2 (3 blade, 13 3/4 diameter), but I would be suprised if you don't have a wicked mid-range porpoise without trim tabs to control it...

 

[schlosser1]

the motor is a 260 hp 350 i tried the vengeance prop yesterday the boat was 1mph faster at 4200 rpm i didn't buy it. my 21 cleaver seems to be the best so far i think i just need more power my old 330hp enchanter use to spin the same prop at 5200 different boat though the dip is awesome think it needs a cam and heads. or a nice 383

 

[wca_tim]

the motor is a 260 hp 350 i tried the vengeance prop yesterday the boat was 1mph faster at 4200 rpm i didn't buy it. my 21 cleaver seems to be the best so far i think i just need more power my old 330hp enchanter use to spin the same prop at 5200 different boat though the dip is awesome think it needs a cam and heads. or a nice 383

just based on my boats performance with a stock drive (I've had an alpha ss on it for a while, but smoked it Sunday and so am putting my spare alpha drive back on it), and that you're running a 1.47/1.5 gear outdrive, you're probalby looking at high 50's to low 60's with that boat (before lightening the load and cleaning up the hull) and with the power you're running, etc... to be propped right for your current power level... I'm betting you would be hard pressed to beat a 19" or maybe 21" laser 2 or something similar...


Are you running stock manifolds? (thinking about weight), have you weighed the boat? (the foam boxes in the engine compartment on mine were originally filled with water as was a lot of the area and foam under the deck...). any pics of how low it sits in the water? (unfortunately I don't think I have any pics of mine in the water...). are you running any exhaust through the prop? what's the running surface look like? trim tabs installed? what conditions? (sorry for the interrogation, just thinking about the situation...)


I was running mid to high 80's with the ss drive and a 26" prop (1.32 gear ratio drive), and about 450+ horsepower at 5500 rpms. Before the head and carb swap, probably a bit over 400 horsepower and more weight in the ass end (cast iron heads), I was running upper 70's ie 77 with a standard alpha drive. Note that was with a 1.84 gear ratio and a taller prop - definately worth 5 mph or so. I've run 1.32, 1.5, 1.62 and 1.84 gear ratios now, and taken the time to prop each one. I've played with the boat a lot over the past couple of years and I think yours is pretty similar. post more info and I'll be happy to help how ever I can...

Cheers! Tim

 

[RLCBoats]

was that an i/o or outboard?

I/O

 

[schlosser1]

sorry to here about your drive my boat could use a polishing underneath, no trim tabs, i haven't checked the foam yet i know the wood in the engine compartment is kinda crappy. stock manifolds cant afford good ones now, exhaust is just through the bellow right now.does that make a difference? i want thru hull but haven't collected all my parts yet i have 3" tips just need some flexy hose or s bends and hose. verry mild chop if any on lake. i watch the vid of your boat all the time and would love to see more. no pics yet will try soon, the lake is 45 min. away so its hard to get there sometimes. let me know if that covers the bases for now. thanks

 

[RLCBoats]

my 88 diplomat does the best with stern lifting props with a stock length drive on it - especially at higher speeds. I'm
I'd also dare say that a quad iv is WAY too much prop for that boat. That's a 15 - 15 1/2 inch prop.

The Quad IV OT is a transom lifting prop and its only 14.5 diameter.

 

[schlosser1]

so maybe i should keep the prop i have and just try for more power seeing the cleaver is a stern lifting prop?

 

[RLCBoats]

so maybe i should keep the prop i have and just try for more power seeing the cleaver is a stern lifting prop?

Correct cleaver gives you stern lift and a chopper style gives you added bow lift. But remember not all Cleavers are created the same or even work the same. Look around and see if you can find a used quade IV OT 22 pitch hydramotive prop you won't be disapointed.

 

[schlosser1]

will do. i tried a 19p quick silver prop yesterday and a 23p vengeance prop a couple days ago my 21p cleaver feels almost as good as the 19 down low and only 2-3 mph less at the top than the 23p. 57-58 on gps with 2 people and crap in the boat

 

[schlosser1]

wet foam and wood next to motor one side out one to go. i had a 305 carb on it so i put 350 metering rods and jets in it. must spin prop faster

 

[franklyoujest]

I have 83 Exciter with a stock 350I/O. it came with 23p cleaver on it. Top speed was 65mph GPS but I didn't like the way it came out of the hole too much bow lift or how it handled in the turns. In the corners it was like what the hell was that. Kind like skips a tooth or something.
So I read up as much about props for my size boat that I could find here and there. I decided on a 5blade prop I’m not a 100% but I think it was 21p 13~14 DIA. I found one for $100 but it was for an outboard so I put on my engine lathe a cut it back (the shaft on the I/O is longer than the O/B).
Anyways I haven’t got top end yet but I tell ya the boat is not the same boat it jumps out of the hole like it should and in the corners it just grips so smooooth.
If you can find a cheap 5 blade prop give it a try it will be worth it.

 

[wca_tim]

Correct cleaver gives you stern lift and a chopper style gives you added bow lift. But remember not all Cleavers are created the same or even work the same. Look around and see if you can find a used quade IV OT 22 pitch hydramotive prop you won't be disapointed.

my apologies on the assumption in t post above - I would second that the smaller diameter quad iv would e a great prop on your boat (and mine as well probably...). although with the ss drive, I need a lot less prop diameter to keep hold. It's like night and day with respect to that.

Right now I'm running a stock alpha with 1.62 gearing and a BBlades cut and labbed 28" mach sterndriver with the diffuser ring removed...

With the stock alpha drive and a load in the boat, it does the mid rom porpoising thing to the point of annoyance unless I use the trim tabs to keep it under control or trim it in to keep the bow down (at a substantial cost to performance and fuel economy). but we're mainly pulling skiers and boarders, tubing, et... right now anyhow...

I gaurantee there are a lot better options than a cleaver on your boat. and hydromotive props are some of the best neutral lift performance props around for i/o set ups with some power... in my experience anyhow.

I ran a 29" pitch 15.5" diameter forit rocked, held like the boat was on rails, but was giving up a bit too much to turn those big blades.. and thatw as with a 1.84 gear ratio so when I burnt that upper gear set up, I went a different route...

If you're looking for all around performance, a 3 or 4 blade is going to be the ticket. a five blade in a little lowed pitch would be great for water sports, etc... but is going to give up a lot on the top end...

if you want to go faster, more power is the main ticket... and will require a different prop anyhow.

first thing I think you probably need to do is to check your transom for rot... and get the rotten, waterlogged wood and crap out of your engine compartment... you're loosing a LOT of performance from the hundreds of pounds of water you're carrying around... and may be flirting with disaster if everything is rotten and soft...

 

[schlosser1]

i had the boat in sebago lake in main for a week and just got back rough ride in mild chop water i noticed i had to keep the boat trimmed down all the way in chop so my head wouldnt pop off it might need trim tabs even on smooth water you get bouncy do the tabs make the boat feel longer or is that size boat mainly made for ponds and rivers??