3 blade to 4 blade

[ken52]

I am trying to raise my wot rpm's and I'm trying to keep my boat on plane at lower rpm's. Don't have room to install trim tabs due to kicker motor mount and swim platform. I've played with raising motor and found best spot IMO.

I have a 1987 ProLine 21 wac (about 3300 lb loaded) with 1987 140 Rude. WOT is 5400 @ about 34-35 gps speed.

Running unknown mfg Al prop 13 3/4 x 15.

Would going down to a 13 pitch do the job?

Any help or suggestions greatly appreciated.

 

[junior1113]

Re: 3 blade to 4 blade

a 3 blade stainless steel prop of same dimensions will give you a little more rpm and better performance. 4 blades have great hole shots and slower plaining speeds and better mid range fuel economy only bad is you lose 1-3 mph top end. you would need to go to a 13 or 14 4blade

 

[H20Rat]

Re: 3 blade to 4 blade

**deleted**

 

[ken52]

Re: 3 blade to 4 blade

Thanks guys, according to my Evinrude service manual it says NOT to use a ss prop on the 140. Also with the water over here in the gulf being very shallow at times I'd rather replace a prop as apposed to lower unit parts.

It looks like my best try would be a 13 pitch. Be nice if we had a place that had test props to try first. I guess if I didn't like it I could try to resell.

 

[Dhadley]

Re: 3 blade to 4 blade

The prop plays a major role in holeshot and planing speed. Alos, with todays 4 blade props it's not unusual to find a good 4 blade matched correctly to the application is faster than a good 3 blade.

 

[junior1113]

Re: 3 blade to 4 blade

planing speed is more a function of the hull and weight than the prop. (a prop CAN influence it, but very little)

the prop is what moves water it is the most important thing to make sure of good performance with out the prop there is no plaining so how little does this affect plaining speed a 3 blade used alluminum compared to a new 4 blade stainless is very substancial difference could be half the time for a hole shot. what about a high five have you ever even heard of that technology is always improving propellers dont give people false info on something u know little about leave your 2 cents out cause it isnt worth 1 cent

 

[junior1113]

Re: 3 blade to 4 blade

Thanks guys, according to my Evinrude service manual it says NOT to use a ss prop on the 140. Also with the water over here in the gulf being very shallow at times I'd rather replace a prop as apposed to lower unit parts.

It looks like my best try would be a 13 pitch. Be nice if we had a place that had test props to try first. I guess if I didn't like it I could try to resell.

your realy not that bad off with a new 15 3 blade or a 14 4 blade. 13 p 3 blade would consume more fuel

 

[ken52]

Re: 3 blade to 4 blade

Thanks to all. Junior would a 4 blade 13 pitch consume more fuel too?

 

[junior1113]

Re: 3 blade to 4 blade

in most applications its way better in fuel economy. at mid range speeds it will be better, quicker hole shots saves fuel. and wide open it will be close to the same because were not changing the amout of fuel per rpm were changing the speed per rpm. post back with results we like to know. youll be happy

 

[junior1113]

Re: 3 blade to 4 blade

"go2marine" has a 13 p 4 blade solas atima alluminum for 105$ not to bad for an alluminum prop

 

[Tail_Gunner]

Re: 3 blade to 4 blade



http://boatpropellers.iboats.com/Ev.../6201/?**********=117351775&*******=736248143

 

[stevens]

Re: 3 blade to 4 blade

Be nice if we had a place that had test props to try first.

Propgods may operate in your area - great service!

Also, iBoats has an exchange program where you may exchange props that aren't right on the first try, but at a fee.

 

[crb478]

Re: 3 blade to 4 blade

Ken, I went from a 17 pitch 3 blade to a 13 pitch 4 blade solas for the same reasons you are encountering. I have a 1990 sea pro 18ft CC with a 1975 Johnson 115. About 2500 lbs loaded. Before the switch I was only getting about 4800 rpm and a longer hole shot. After the switch I am getting 5300 rpm a quicker hole shot and better all around handling. I did loose about 3 mph on the top end though. I should mention that I have my motor all the way up and could still probably use a jack plate as I have a stepped transom which allows the motor to ride higher than most. My boat also backs up much better than before. I would like to get 3-400 more rpm out of it through fine tuning, but my point is unless you just are looking for speed I think that you will like a 4 blade prop.

 

[junior1113]

Re: 3 blade to 4 blade

http://boatpropellers.iboats.com/Ev.../6201/?**********=117351775&*******=736248143

sorry i boats could'nt find it when i looked

 

[wca_tim]

Re: 3 blade to 4 blade

Note that to help lower planing speed some you're looking for ideally a 4-blade prop with stern lifting characteristics (not bowlifting or high rake!)... I really like the solas titan (not the HR - high rake version) on my set up as well as mercs venusa... an nothing runs better than a hydromotive quad 4.

With a high 5 my experience is that you lose to much on the top end. 4-blade is a very nice comprimise and in some situations can run faster than an analogous 3 blade. even if you lose a couple mph on the top, you'll notice a great big difference in handling, smooth take off, and the like.

Note that tabs would have a more dramatic effect on lower planing speed than prop in most situations...

Also note that I named the stainless props I'm familiar with above... the analogous aluminum ones should be as good...

 

[ken52]

Re: 3 blade to 4 blade

Thanks to all for the great advice. As soon as I can appropriate the funds from by budget dept (aka wife) will order that 4 blade solars from iboat site.
Will keep all advised of results.

WCA wish I had room for trim tabs but the kicker bracket and swim platfrom would restrict installation. Actually thinking about giving up the kicker but not sure that would be the best idea yet.

Kenny

 

[ken52]

Re: 3 blade to 4 blade

Ok, I decided to just get a new 3 blade aluminum prop. I'm looking at 4 props on this site to buy and wonder what the difference would be besides price.

13 3/4 x 15:

Solas Amita, Solas Rubex, Michigan Wheel Vortex and Mi Wheel Match.

Anyone using these that could shed some opinions about them would be greatly appreciated.

 

[GunHoInc]

Re: 3 blade to 4 blade

Just tagging along on your thread here: This is not a hijack buy any means. LOL

I just swapped out my 3 blade SS Quicksilver 14 1/4" x 19" pitch prop for an aluminum Quicksilver 4 blade 14 1/2" x 18" Pitch prop. My WOT rpms with the old prop was within the recommended range and Speed was 41+. But I bought my son a big tube to pull behind the boat. In my opinion even with trim tabs my hole shots were sluggish with a boat load of kids. And I had to do about 23-25 mph to stay on plane. The 3 blade prop seemed to spray alot of water on the kids in the tube so I had to over trim the outdrive, and raise the trim tabs to reduce the spray. This eats up a lot of gas, not to mention I'd like to pull the tube at a slower speed and stay on plane. So I'm going to test out the 4 blade this weekend and I'll post up how it rides. I'm really not worried about a 3 mph drop in top end as my wife says the boats too fast as it is. I'm more concerned about handling. I also had to swap out my anode for a flat one so the prop would fit. I might get one later with an offset.

My boat is a 1986 SeaRay SRV210 CC with a 5.7 I/O Alpha 1

 

[trswenson]

Re: 3 blade to 4 blade

Ok, I decided to just get a new 3 blade aluminum prop. I'm looking at 4 props on this site to buy and wonder what the difference would be besides price.

13 3/4 x 15:

Solas Amita, Solas Rubex, Michigan Wheel Vortex and Mi Wheel Match.

Anyone using these that could shed some opinions about them would be greatly appreciated.

Dude what happened? Everyone suggested a 4 blade to meet your needs and boom you're getting a 3 blade...?
I went from 3 blade 17P to 4 blade 17P (not enough torq) then to 4 blade 15P. All I do is pull toys & people around. All my props have been Aluminum. The 15P 4 blade is awesome, now It's time for the final upgrade to SS. You should really consider the 4 blade Solas Amita

 

[trswenson]

Re: 3 blade to 4 blade

http://boatpropellers.iboats.com/Ev.../6201/?**********=117351775&*******=736248143

Mr. Gunner,
I love your opinions on this site but have to ask about your Quote on the bottom... Did you realy mean to say Stickley or are you forgetting the R & T(Strictly) also it would be 'AN opinion' not 'A opinion'.
I know we're talking boats not GrAmmAr. chastise me as you see fit