Need help picking a High Five

[akorcovelos]

Hi, I'm one of those people trying to make my stern drive into something its not, a wakeboard boat. This plan will have to do until rear wakboard boats come down from lala land in pricing.

Here is the pertinent info:
1) Performance issue you are trying to correct.
Much better hole shot, would like it to be easier to hold a steady speed (18-22mph)

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
I think its a Michigan Wheel Apollo SS.

3) Current prop diameter and pitch (required).
This is the current three blade I'm running:

And this is an aluminum 4 blade I tried that made it worse so Ii switched back:
Took way longer to get up and moving with this one.

4) Wide open throttle RPM and speed with an average load (very helpful)
Two days ago I confirmed a max RPM of 4600 rpm at 43.8 mph on my GPS and the stock tach.

5) Engine/drive make, model, year, and HP
Mercruiser 260/Alpha1 Gen1, '84, 260hp

6) Boat make model, year, length and weight
Webbcraft Riviera 21' BR. Here is the specs from iboats: This inboard/outboard runabout is 21.17 feet long and weighs 3000 (pounds dry). This weight does not account for passengers, fuel, or gear. The beam of this craft is 96 inches.

With all my gear and friends you can add another 1300-1500lbs including the 45gal of fuel its usually hauling, so operational load is in the 4500# range.

My plan is to get a Ridesteady cruise system by spring, but a High Five prop just popped up on CL and I hear these make a huge difference for watersports. The seller knows nothing about the prop other than its 21p, he doesn't know the dia. but is trying to find out for me. What specs should I be looking for in a 5 blade for my boat and application?

Thanks in advance!

 

[dan02gt]

Re: Need help picking a High Five

Hi, I'm one of those people trying to make my stern drive into something its not, a wakeboard boat. This plan will have to do until rear wakboard boats come down from lala land in pricing.

Here is the pertinent info:
1) Performance issue you are trying to correct.
Much better hole shot, would like it to be easier to hold a steady speed (18-22mph)

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
I think its a Michigan Wheel Apollo SS.

3) Current prop diameter and pitch (required).
This is the current three blade I'm running:

And this is an aluminum 4 blade I tried that made it worse so Ii switched back:
Took way longer to get up and moving with this one.

4) Wide open throttle RPM and speed with an average load (very helpful)
Two days ago I confirmed a max RPM of 4600 rpm at 43.8 mph on my GPS and the stock tach.

5) Engine/drive make, model, year, and HP
Mercruiser 260/Alpha1 Gen1, '84, 260hp

6) Boat make model, year, length and weight
Webbcraft Riviera 21' BR. Here is the specs from iboats: This inboard/outboard runabout is 21.17 feet long and weighs 3000 (pounds dry). This weight does not account for passengers, fuel, or gear. The beam of this craft is 96 inches.

With all my gear and friends you can add another 1300-1500lbs including the 45gal of fuel its usually hauling, so operational load is in the 4500# range.

My plan is to get a Ridesteady cruise system by spring, but a High Five prop just popped up on CL and I hear these make a huge difference for watersports. The seller knows nothing about the prop other than its 21p, he doesn't know the dia. but is trying to find out for me. What specs should I be looking for in a 5 blade for my boat and application?

Thanks in advance!

The 21P is more than likely the one you want and is going to be the best water sports prop you can put on your boat. They are a whole different beast and don't follow the normal rules of pitch increasing and decreasing RPMs like your standard 4 and 3 blade props. All High-5s are 13.25" in diameter except the 17" that is 13.5". Make sure you get the right hub kit for it.

 

[akorcovelos]

Re: Need help picking a High Five

Well I talked to the seller and he gave me the number off the prop which is 48-815746 24. I'm being told that this is a 24p prop? Thats way to much for my boat I think. The guy at the local prop shop said a 17p high five would give me the best performance for wakeboarding, so I guess the hunt continues.

 

[dan02gt]

Re: Need help picking a High Five

Well I talked to the seller and he gave me the number off the prop which is 48-815746 24. I'm being told that this is a 24p prop? Thats way to much for my boat I think. The guy at the local prop shop said a 17p high five would give me the best performance for wakeboarding, so I guess the hunt continues.

That's odd Mercury current only makes the High-5 in odd pitch, but it could be a older small hub one. At any rate you don't want it.

I wouldn't go any lower than a 19 pitch High-5 for your setup. I think you would be all over the rev limiter with a 17 and it will kill your cruising economy.

 

[jestor68]

Re: Need help picking a High Five

The Mercury prop selector will give you an accurate recommendation for a "high five" prop if you plug in accurate numbers.

Give it a try. With the weights you're talking, you might be surprised at the answer.

Hint; your local shop guy is on the right track.

 

[akorcovelos]

Re: Need help picking a High Five

I gave it a shot and it said 21p 13.25dia for the high five.

 

[dan02gt]

Re: Need help picking a High Five

I gave it a shot and it said 21p 13.25dia for the high five.

Yep that's the one I would run, but if you want a little more hole shot go with the 19P. Like I said before the High-5 is it's own beast and you can't compare it to other props of similar pitch in 3 and 4 blade.

My stepfather had a 20' Astro Bass Boat with a 200 Merc EFI on it years ago. It had a High-5 on it and let me tell you it was nasty out of the hole, but it sacrificed top speed.

 

[jestor68]

Re: Need help picking a High Five

I gave it a shot and it said 21p 13.25dia for the high five.

Try again.

Using your stated performance; it says a 19 pitch "five". Using your stated weight; it says a 17 or 19 pitch "five".

What's your gear ratio? I used 1.62, because that's the only gear ratio that yields a realistic slip number(14%) using your stated performance data.

A 21 pitch might make a nice cruising prop, but I thought you were looking for hole shot and speed holding at 18-22 mph.

 

[Bondo]

Re: Need help picking a High Five

Try again.

Using your stated performance; it says a 19 pitch "five". Using your stated weight; it says a 17 or 19 pitch "five".

What's your gear ratio? I used 1.62, because that's the only gear ratio that yields a realistic slip number(14%) using your stated performance data.

A 21 pitch might make a nice cruising prop, but I thought you were looking for hole shot and speed holding at 18-22 mph.

Ayuh,.... With the 260hp, V8, it oughta be 1.5:1,...

 

[akorcovelos]

Re: Need help picking a High Five

I believe Bondo is correct, its a 1.5:1 SEI A1G1.

So then a 17p 13.5" five wouldn't be advisable? One just popped up on CL near me for $375obo. Oh, and your correct jestor68, my primary concern is hole shot and holding 18-22mph with as little effort as possible. Not too concerned with top end performance at all. I can throw my 3 blade back on for long cruising days.

 

[jestor68]

Re: Need help picking a High Five

The selector doesn't offer that gear ratio because it only goes back to the year 2000.

The gear ratios shown are the current gear ratios ( 1.47, 1.62, 1.81 ). Since your ratio falls between the first two, the outcome would be similar. Both of those ratios called for a 19, or a 17 if you're really serious.

The 19 pitch would provide adequate acceleration and speed holding, while the 17 would be the "kill" setting.

You won't over rev the motor unless you jam the throttle wide open and leave it there(which is what would happen with any specialized water sports prop).

According to the SEI web site, their Gen One drive for the 198-260 hp is a 1.47 gear ratio.

It may seem strange; but the 17 pitch "Five" should give almost the same top speed(42-44) you're getting now with the 3 blade at 4600 rpm, due to less slippage.

According to the SEI web site, their Gen 1 drive for the 198-260 hp is a 1.47 gear ratio ( not that it makes any difference ).

 

[akorcovelos]

Re: Need help picking a High Five

I didn't realize the SEI was different from original. I'm supposed to check out the 17p on Saturday, looks like a nice prop though. It would be awesome to get to try the five this season.

 

[smokeonthewater]

Re: Need help picking a High Five

I think you are barking up the wrong tree... for all around use the high five would be nice but for your STATED GOAL try a 15 x 16 aluminum 4 blade... it is cheap and will do a much better job at what you want to do

Will give you a neck snapping hole shot if you hit it hard enough and will be very easy to hold the low planing speed you want because the engine won't be working near as hard as it would with a higher pitch.

Obviously it wouldn't work for top speed and you would need to back off the throttle at high speed to prevent over revving but then you already HAVE a prop for speed runs

 

[akorcovelos]

Re: Need help picking a High Five

From what I've been reading the 4 blades don't do as well on bigger boats like mine. I know the 14 x 20 aluminum 4 blade I have is terrible. I lost hoke shot and top end with it. Not to mention the chain of lakes I boat on is pretty shallow and aluminium props don't last long. It took all of a week to take a chunk off one of the blades on the aluminium prop where my SS prop that came with the boat still looks great.

 

[akorcovelos]

Re: Need help picking a High Five

Picked up a Quicksilver QST 5 in 13.5 x 17p! Rain kept me off the lake today, but hopefully I'll get out to test it tomorrow or Monday.

 

[dan02gt]

Re: Need help picking a High Five

I bet she'll get out of the hole now.

On a side note that orange stuff on your transom is marine polyurethane adhesive designed for below waterline use and not regular old silicon RTV right?

 

[akorcovelos]

Re: Need help picking a High Five

Probably not...it was one of the many issues I inherited from the PO...Hasn't concerned me too much since the boat is only in the water for a couple hours per week, but I need to fix that since I plan to leave it in the water next year.

 

[smokeonthewater]

Re: Need help picking a High Five

From what I've been reading the 4 blades don't do as well on bigger boats like mine. I know the 14 x 20 aluminum 4 blade I have is terrible. I lost hoke shot and top end with it. Not to mention the chain of lakes I boat on is pretty shallow and aluminium props don't last long. It took all of a week to take a chunk off one of the blades on the aluminium prop where my SS prop that came with the boat still looks great.

the problem with your current 4 blade is the 20" pitch... way too much.... your new 5 blade will work great for all around use and there is no denying that SS is stronger but I still say that a cheap 16" pitch prop... be it an elephant ear 3 blade or a 4 blade will hole shot better than the 17 if you find that you want a dedicated tow prop.

btw never have I heard that a 4 blade prop isn't good for a "bigger boat" and I wouldn't consider 21' to be a "bigger boat"

recently I put one on a single engine 27' cruiser and got excellent results

 

[akorcovelos]

Re: Need help picking a High Five

I'll have to see how I like the 5 blade, but aluminum props are cheap around here mostly because they are looked at as disposable. They really don't last in the waters I boat in which is the biggest problem I had with mine. I could grab a 4 blade aluminum for $75 and see if the 16p is better than the 5 blade, and if it is I can find a SS one to buy.

 

[smokeonthewater]

Re: Need help picking a High Five

well it will likely do better at holeshot and towing but for cruising and top speed the 17p will likely be better.... run what you have first and go from there... I view alum props as disposable too.... kinda like gas... ugh