Merc Alpha4 no longer available. What to replace it with?

[QBhoy]

To give this thread some completion, I'll update it now.

After having phoned all the local boat shops, and visiting a few specialist prop shops, nobody had a Rev4, 17"... So I placed a 'Wanted' ad in our local Gumtree (website, not actual tree). A week ago a guy calls me and says he has one. Great! Then he gets home and checks, it's an 'Offshore', not a Revolution4, but it is 17" pitch. Anyway, I bought it, having had Offshore props on my old drive...

Took it for its first spin today (pun intended).... With 2 up, 145L of petrol in the tank and 2 sets of scuba gear, hit the rev limiter (4950) at 38knots. Felt really really smooth, and the hull just did what it wanted (no bow lift!). The boat felt great, the best it's felt for a long time. Cruising speed is up by about 8 knots! The trim control was solid, it came out of the water quickly and with far less stern 'ploughing'... I'm very happy with it...

As an aside (and I think @QBhoy will find this funny), the guy was trying really hard to get me to try an Enertia (3 blade) prop, promising I'd really love it...

Chris..........

Haha. I like this guy...him and I could be good friends

 

[QBhoy]

To give this thread some completion, I'll update it now.

After having phoned all the local boat shops, and visiting a few specialist prop shops, nobody had a Rev4, 17"... So I placed a 'Wanted' ad in our local Gumtree (website, not actual tree). A week ago a guy calls me and says he has one. Great! Then he gets home and checks, it's an 'Offshore', not a Revolution4, but it is 17" pitch. Anyway, I bought it, having had Offshore props on my old drive...

Took it for its first spin today (pun intended).... With 2 up, 145L of petrol in the tank and 2 sets of scuba gear, hit the rev limiter (4950) at 38knots. Felt really really smooth, and the hull just did what it wanted (no bow lift!). The boat felt great, the best it's felt for a long time. Cruising speed is up by about 8 knots! The trim control was solid, it came out of the water quickly and with far less stern 'ploughing'... I'm very happy with it...

As an aside (and I think @QBhoy will find this funny), the guy was trying really hard to get me to try an Enertia (3 blade) prop, promising I'd really love it...

Chris..........

Offshore is a good prop by all accounts. Never tried one though. Good going chris

 

[QBhoy]

Chris can’t remember if you said or not...can you remember any figures from your test with the new prop ? How did they look ? Rpm and gps top end etc ? Does she cruise with less effort now too ? What was she happiest sitting at cruising speed, rpm and speed wise ?
I found my cuddy outboard boat actually used less fuel with a 19” pitch over the 20” pitch. At the cruising speed it’s happiest at (about 25 mph), despite the rpm obviously being about 80-100 rpm more than the higher pitch. Not the same type of prop to be fair. But interesting and enough to make me run the lower pitch most of last year. Was much happier with the 19” everywhere really, except top end. I’ve lifted the engine just the other day there. To where it should be. Wee bit of prop testing to do soon, I’d think. With it perhaps performing a little different to previous

 

[achris]

Chris can’t remember if you said or not...can you remember any figures from your test with the new prop ? How did they look ? Rpm and gps top end etc ? Does she cruise with less effort now too ? What was she happiest sitting at cruising speed, rpm and speed wise ?

Max revs. Hit the rev limiter at 4950.
Speed at max revs. 38 knots.
Because the prop offers no bow lift the hull performs much better, and I'm able to cruise at between 5 and 8 knots faster for a given sea.
The 'holeshot' was definitely quicker and the boat tended not to 'squat' as much, it came onto the plane 'flatter'. The prop was definitely less susceptible to 'weeding' and atone point I was running a fairly high trim and we had to slow down and drop off the plane. Didn't come to a full stop, but when I went to accelerate back up (with the drive still at a high trim angle) the prop ventilated (indicating weed). Quick reverse throw the weed and we were off again, but the point was that I hadn't even felt the weed being picked up. If I'd been running the 3 blade, it would have ventilated immediately and in order to keep run I would have had to trim right in...

Best cruising speed in the Indian ocean is VERY dependent on the weather. Some days it's as low as 13 knots, others I've headed out at WOT and not pulled the throttle back for the whole run (14Nm)... The day I was out with the Offshore would have been a 19 knot day with the 3 blade, but with the 4 blade, it was a 29 knot day.

Here's a screengrab of my Angle of Attack calculator...



HTH,

Chris........

 

[QBhoy]

Max revs. Hit the rev limiter at 4950.
Speed at max revs. 38 knots.
Because the prop offers no bow lift the hull performs much better, and I'm able to cruise at between 5 and 8 knots faster for a given sea.
The 'holeshot' was definitely quicker and the boat tended not to 'squat' as much, it came onto the plane 'flatter'. The prop was definitely less susceptible to 'weeding' and atone point I was running a fairly high trim and we had to slow down and drop off the plane. Didn't come to a full stop, but when I went to accelerate back up (with the drive still at a high trim angle) the prop ventilated (indicating weed). Quick reverse throw the weed and we were off again, but the point was that I hadn't even felt the weed being picked up. If I'd been running the 3 blade, it would have ventilated immediately and in order to keep run I would have had to trim right in...

Best cruising speed in the Indian ocean is VERY dependent on the weather. Some days it's as low as 13 knots, others I've headed out at WOT and not pulled the throttle back for the whole run (14Nm)... The day I was out with the Offshore would have been a 19 knot day with the 3 blade, but with the 4 blade, it was a 29 knot day.

Here's a screengrab of my Angle of Attack calculator...

View attachment 337240

HTH,

Chris........

Cheers chris. Fair bit of slip...but main thing is it seems to be doing just what you want it to. Good result, that being the case.

 

[achris]

Just to update this topic.
I also managed to find a 19" Vensura (same as an 'Offshore') and have just done the final trials. The 17" Offshore allowed the engine to get to the rev limiter, a bit too easily, hence I sort out a 19". Unfortunately the 19" pulls the revs down to 4650rpm, with only myself and 100L of fuel. Too low for my liking. So, if anyone wants a 19" Vensura...

I've done speed and fuel usage figures, and here's what they both look like... (note that for the same BOAT speed, the fuel usage is very much the same, regardless of pitch.)





As a final comment, and to close out this thread. Either 4 blade is so different to the 3 blade props I have used. Even the Admiral noticed the difference, and slap me around for not changing it years ago.

Chris......

 

[QBhoy]

Just to update this topic.
I also managed to find a 19" Vensura (same as an 'Offshore') and have just done the final trials. The 17" Offshore allowed the engine to get to the rev limiter, a bit too easily, hence I sort out a 19". Unfortunately the 19" pulls the revs down to 4650rpm, with only myself and 100L of fuel. Too low for my liking. So, if anyone wants a 19" Vensura...

I've done speed and fuel usage figures, and here's what they both look like... (note that for the same BOAT speed, the fuel usage is very much the same, regardless of pitch.)

View attachment 340251

View attachment 340252

As a final comment, and to close out this thread. Either 4 blade is so different to the 3 blade props I have used. Even the Admiral noticed the difference, and slap me around for not changing it years ago.

Chris......

Chris. Love this. Am I reading that right to think you are getting 40 knots with the bottom graph ? Probably not reading it right to think you’re getting 1.5 miles per litre at full throttle though, am I ?

 

[achris]

Chris. Love this. Am I reading that right to think you are getting 40 knots with the bottom graph ? Probably not reading it right to think you’re getting 1.5 miles per litre at full throttle though, am I ?

Right on speed. But 1.5L/nm @ 40 knots. (about 2.9miles/USG @ 46mph)

 

[achris]

..Fair bit of slip...

Actually not as much as it looks like. Here's the 2 props.
The 17"


The 19"


Something to be aware of is that my calculator adds an inch to the inputted pitch to account for blade cupping. None of the online ones I've seen do that... If I remove that extra inch, the slip comes out at 11.3% (that's what you'd see with one of the online calculators. )

 

[Scott06]

Cheers chris. Fair bit of slip...but main thing is it seems to be doing just what you want it to. Good result, that being the case.

I had 20 % slip with a vensura on my boat, but the slip allowed better holeshot as the engine would get in its power band sooner.
chris seeing your results which mirror mine with vensura, you will really want to try a revolution 4 17” at some point. I lucked out and found an essentially new one on ebay for $300 was worth the wait

 

[achris]

I had 20 % slip with a vensura on my boat, but the slip allowed better holeshot as the engine would get in its power band sooner.
chris seeing your results which mirror mine with vensura, you will really want to try a revolution 4 17” at some point. I lucked out and found an essentially new one on ebay for $300 was worth the wait

I tried a 19" Rev4, and loved it, but too much pitch. I'm still looking for 17", so if you see one, think of me....

 

[Scott06]

I tried a 19" Rev4, and loved it, but too much pitch. I'm still looking for 17", so if you see one, think of me....

Mercury Revolution 4 Propeller Prop 14 5/8 X 17" Pitch RH 48-857024a46 17p for sale online | eBay

Find many great new & used options and get the best deals for Mercury Revolution 4 Propeller Prop 14 5/8 X 17" Pitch RH 48-857024a46 17p at the best online prices at eBay! Free shipping for many products!

www.ebay.com

not sure what your defintion of cheap is...especially considering shipping down under.

 

[achris]

Mercury Revolution 4 Propeller Prop 14 5/8 X 17" Pitch RH 48-857024a46 17p for sale online | eBay

Find many great new & used options and get the best deals for Mercury Revolution 4 Propeller Prop 14 5/8 X 17" Pitch RH 48-857024a46 17p at the best online prices at eBay! Free shipping for many products!

www.ebay.com

not sure what your defintion of cheap is...especially considering shipping down under.

Yeah, with shipping, that's close to the new price better. Thanks for looking though.

 

[Scott06]

Mercury Revolution 4 14 5/8 x 17 Stainless Steel Propeller 48-857024-17 | eBay

The Revolution 4 four blade stainless steel propeller has excellent holding and speed. In many cases this prop is faster than a Bravo 1 Performance prop. The Revolution 4 stainless steel propeller turns high horsepower into performance for single through quint center consoles, bay, walleye...

www.ebay.com

this one is better cost wise. I just set up a search get pinged when they list

 

[andrejpesockij920]

what do you think about the 19 "Rev4 can someone give feedback?
spaisbo
Best, Andrey

 

[Scott06]

I think the rev 4 in general is an excellent prop but prop choice depends on your boat and how you want to use it. I get great holeshot, stern lift, and ability to trim out with the Rev 4.
the pitch will depend on your boat and what its current engione/prop combo delivers in terms of WOT rpm and what performnace improvements you are looking for.

Not trying to be unfreindly but you would be best served by starting your own prop thread, give us the details on your boat, engine, current prop/wot rpm, and what you are looking to improve.

 

[achris]

what do you think about the 19 "Rev4 can someone give feedback?
spaisbo
Best, Andrey

I think the rev 4 in general is an excellent prop but prop choice depends on your boat and how you want to use it. I get great holeshot, stern lift, and ability to trim out with the Rev 4.
the pitch will depend on your boat and what its current engione/prop combo delivers in terms of WOT rpm and what performnace improvements you are looking for.

здороваться Andrey. To expand on Scott's comments. My boat has a very deep Vee, and as such when accelerating from below planing speed the bow tends to rise as it's 'climbing the hill'. The 4 blade props in general, and the Rev4 in particular generate a good deal of 'stern lift', so it tends to push the stern up as the bow is trying to rise naturally. This gives me a quicker planing time and a lower planing speed. It also helps a lot as my wife likes to ride in the back (less bumps). I also notice, with my hull, a lot less 'slamming' at cruising speeds, and that leads to being able to cruise a bit quicker with a softer ride. I picked up a full 5 knots with the 4 blade over a 3 blade. For me a 4 blade propeller is очень хороший

... you would be best served by starting your own prop thread, give us the details on your boat, engine, current prop/wot rpm, and what you are looking to improve.

Definitely this... ^^^

Chris......

 

[Stinnett21]

I think the rev 4 in general is an excellent prop but prop choice depends on your boat and how you want to use it. I get great holeshot, stern lift, and ability to trim out with the Rev 4.
the pitch will depend on your boat and what its current engione/prop combo delivers in terms of WOT rpm and what performnace improvements you are looking for.

Not trying to be unfreindly but you would be best served by starting your own prop thread, give us the details on your boat, engine, current prop/wot rpm, and what you are looking to improve.

Scott, to confirm, the results you state in your second sentence above are with the 2004 Sea Ray 200 sport?

 

[Scott06]

Scott, to confirm, the results you state in your second sentence above are with the 2004 Sea Ray 200 sport?

correct, it has a 5.0 carb that is stock except for a 4 bbl intake and edlebrock 1409 carb

 

[andrejpesockij920]

what do you think about the 19 "Rev4 can someone give feedback?
spaisbo
Best, Andrey

I think the rev 4 in general worktime is an excellent prop but prop choice depends on your boat and how you want to use it. I get great holeshot, stern lift, and ability to trim out with the Rev 4.
the pitch will depend on your boat and what its current engione/prop combo delivers in terms of WOT rpm and what performnace improvements you are looking for.

Not trying to be unfreindly but you would be best served by starting your own prop thread, give us the details on your boat, engine, current prop/wot rpm, and what you are looking to improve.

What improvements are you looking for and what is important to you? I'll be grateful for my own. I'm new to this business.