My O/B Skater and new TU CNC 4 blade props

[appsyscons]

What follows below, is my opinion, based on my testing. You should consult a professional, before attempting any of these tests or changes yourself.

<O:p</O:pThis past weekend, I tried the Throttle Up CNC 14.75 x 31 4 blade props, on my boat, 30 Skater T/300XS. Compared to the 3 blade props they worked better at getting the boat on plane, quicker, easier, less vibration, they had better midrange acceleration, and wot performance, was 0.4mph faster. They do cause some additional stern lift, over 3 blade props, which makes the boat feels a bit looser, but it is manageable and water pressure is above 10lbs.

<O:p</O:pIn total, we have tried 8 different propellers:
<O:p</O:p
Merc Racing 14.5 x 32, 3 blade cleaver, lab finished<O:p</O:p
Merc Racing 14.5 x 34, 3 blade cleaver, lab finished
Merc Racing 15 x 32, 3 blade cleaver, double lab finished<O:p</O:p
Merc Racing 15 x 32, 3 blade cleaver, lab finished<O:p</O:p
Throttle-Up CNC 15 x 30, 5 blade, cleaver<O:p</O:p
Throttle-Up CNC 14.75 x 30, 5 blade, cleaver<O:p</O:p
Throttle-Up CNC 15 x 31, 4 blade, cleaver<O:p</O:p
Throttle-Up CNC 14.75 x 31, 4 blade cleaver

We have also tried 8 different setups:<O:p</O:p

Props turning in<O:p</O:p
Props turning out
Prop shaft height, 7/8 above bottom<O:p</O:p
Prop shaft height, 1 1/2 above bottom<O:p</O:p
Prop shaft height, 1 5/8 above bottom<O:p</O:p
Prop shaft height, 1 3/4 above bottom<O:p</O:p
Toe out 1/4<O:p</O:p
Toe 0

The best setup is, 1 3/4 above the bottom, toe 0, props turning in, and a bottom modification “water ramps” to get the necessary water pressure.

The 5 blade props just have way to much stern lift for my boat, which leave the best 3 blade and the best 4 blade prop. They are the MR 15 x 32, 3 blade cleaver, lab finish, and the TU CNC 14.75 x 31, 4 blade, cleaver.

Here are the back to back runs for the 2 best props:

Weather underground, NOAA, National Weather Service, and Weather Channel, reported the following at the time of my runs:<O:p</O:p
Air temperature low/mid 90s<O:p</O:p
Humidity 67% - 90%<O:p</O:p
Heat index 105-110

MR 15 x 32, 3 blade cleaver lab<O:p</O:p
TU CNC 14.75 x 31, 4 blade cleaver

PORT STBD AVG MPH SLIP<O:p</O:p
MR 5837 6005 5921 97.3 9.32%<O:p</O:p
MR 6025 5909 5937 97.9 9.46%
MR 5994 6009 6002 99.7 8.32%
<O:p</O:p
TU 6029 6216 6213 99.2 10.59%<O:p</O:p
TU 6042 6257 6150 99.4 10.80%
TU 6072 6261 6186 100.1 10.44%

I scored each prop in 4 categories; getting on plane, mid range acceleration, wot speed, and handling, giving 1 point to the prop that won each category. The final score

3 points = TU CNC 14.75 x 31, 4 blade, cleaver<O:p</O:p
1 points = MR 15 x 32, 3 blade cleaver, lab finish

For me, the Throttle-Up CNC 14.75 x 31, 4 blade cleaver, are my propellers of choice and will remain on my boat.<O:p</O:p<O:p</O:p<O:p</O:p

[Diamond Performance]

Looks good Frank, no more stern lift with the 4 blades vs 3 blades?

[appsyscons]

Looks good Frank, no more stern lift with the 4 blades vs 3 blades?

YES more stern lift, I wrote "They do cause some additional stern lift, over 3 blade props, which makes the boat feels a bit looser, but it is manageable and water pressure is above 10lbs"

It is the nature of the beast, more blades, euqals more stern lift. The boat has a slightly different angle of attack, but not crazy like the 5 blade props, or the 15 in diam 4 blade props. If you have seat time in the boat, you can notice and feel the difference immediatly. In my opinion, I can manage it.

[Maritime_Eng]

Nice Work Frank. Sounds like the boat is running good. Looking forward to getting out and running with you this fall.

[appsyscons]

Nice Work Frank. Sounds like the boat is running good. Looking forward to getting out and running with you this fall.

How are you doing with yours?

[Maritime_Eng]

How are you doing with yours?

Mine is running really well. I keep making small adjustments and I have picked up a few more mph. Boat feels much better with the 4 blades turning in, it flys level in the rough and does not porpus as bad in calm water.

[dkwestern]

Great testing! Exhausted plenty of props

[hotbeek]

Is that typical to have such high slip numbers ? or is that typical of cleavers ?

I know Throttle Up was given some pretty good kudos over on "Speedwake" I also heard Julie is not "hard on the eyes" either !!!

Congrats !

[hotbeek]

Have you tried any higher propshaft heights ? Seems like you got your best results at 1 3/4". Did you try any higher or was water pressure falling off ?

[appsyscons]

Is that typical to have such high slip numbers ? or is that typical of cleavers ?

I know Throttle Up was given some pretty good kudos over on "Speedwake" I also heard Julie is not "hard on the eyes" either !!!

Congrats !
<O:p</O:p
The higher slip on the Throttle-Up props compared to the MR props, is due to the reduced diameter, which was necessary to reduce the additional lift caused by the 4 blade props.

Not only were the TU 4 blade faster than the MR 3 blade, but they were more consistant in top end speed.<O:p</O:p<O:p</O:p

[appsyscons]

Have you tried any higher propshaft heights ? Seems like you got your best results at 1 3/4". Did you try any higher or was water pressure falling off ?

At 1 3/4 pressure was already to low, that is why I put the water ramps in. If I went higher I would probably add some more speed, but the lack of water pressure might make it problematic. If it was a 'race boat' I would risk it and go higher.

[Umassot50]

how much money have you spent testing all these props? how much do your props of choice cost you?

[tux974]

Great detailed info. Will save some trial & error and gives a good baseline :thumbsup:

[appsyscons]

how much money have you spent testing all these props? how much do your props of choice cost you?

MR props were borrowed, TU props were all custom made for me. A, not so small, fortune, in both time and money, has been spent to get this boat to this point. Throttle-Up Propellers, Page Racing, Bullock Marine, Douglas Marine Skater, TNT, Mercury Racing and All Fiberglass Repairs, have all been involved at various stages.

For pricing on Throttle-Up props, call Jullie at 727-531-2255

Thanks to all
Frank Fasulo

[mjwalters]

most tunners are overly concearned with the slip numbers, I feel ,forget the slip and go with the fastest props. I have had experience over the years that indicate low slip % do not always reflect fastest speed

[appsyscons]

most tunners are overly concearned with the slip numbers, I feel ,forget the slip and go with the fastest props. I have had experience over the years that indicate low slip % do not always reflect fastest speed

Exactly right!

[hotbeek]

most tunners are overly concearned with the slip numbers, I feel ,forget the slip and go with the fastest props. I have had experience over the years that indicate low slip % do not always reflect fastest speed


That's what I believe also but slip numbers will indicate efficiency. Obviously the lower the slip the more efficient the prop so you're not being as efficient with the higher slip numbers. I was just wondering if the cleavers were the best props ?! Generally tunnel hull/cats have relatively low slip numbers. Maybe it's the twin engine setup that induces the higher slip numbers ? or turning props in ? I realize that you've done a lot with your testing just wondering what's left out there yet ?!

[mjwalters]

Most often the slip # for a skater are in the single digits I know nothing of this set up But it seems that the owner has worked hard to find the best setup...
Is this a 24' hull or a 28' boat?

[appsyscons]

That's what I believe also but slip numbers will indicate efficiency. Obviously the lower the slip the more efficient the prop so you're not being as efficient with the higher slip numbers. I was just wondering if the cleavers were the best props ?! Generally tunnel hull/cats have relatively low slip numbers. Maybe it's the twin engine setup that induces the higher slip numbers ? or turning props in ? I realize that you've done a lot with your testing just wondering what's left out there yet ?!

As I understand it, as you increase the number of blades, you increase the stern lift. Also cleaver design blades have less stern lift than round ear blades.

The high slip is a function of the small diamater, which is necessary to reduce stern lift.

I do not really know what other prop vendors have, and unless something changes, I am going to run it as it is today. I need to get some fun out of it.

[olmo40]

Great post , :thumbsup:I love to see people doing real world testing .I used to keep a set of B1s lurking for mine as well ,They were a good every day prop .

Did you ever consider the MR 4 Bladers ?

[hotbeek]

I hear ya ! I changed so much on my setup over the winter(WI) that I've spent half my summer dialing in my setup AGAIN ! I now think I have my sweet spot for propshaft and prop. Once I feel I have it "perfect" I'll make my speed passes and then send my prop off for lab finishing. That will be the end of my season !:mad:

[hotbeek]

Can they tweak your "port" prop to get an extra 200 rpms to match the "starboard" side ? or is that an engine thing ?

[appsyscons]

Great post , :thumbsup:I love to see people doing real world testing .I used to keep a set of B1s lurking for mine as well ,They were a good every day prop .

Did you ever consider the MR 4 Bladers ?

In one word NO.

The boat came with MR 3 blade cleavers, and I had one throw a blade after 15 hours. It took 60 days to get a replacement from MR. The first weekend after the replacement prop came, after 1 hour of use, the other side threw a blade, it had 16 hours on it. This time the replacement came in 24 hours. I knew it was time to find another prop vendor.

[appsyscons]

Can they tweak your "port" prop to get an extra 200 rpms to match the "starboard" side ? or is that an engine thing ?

Might be the crazy heat and humidity, time will tell.

Still under MR warranty, so I am not interested in any changes to engines, unless it is to correct something, covered by the warranty. At some time in the future, after the warranty is up, I may dyno them, and then add some power to each and then dyno them again.

[2scoops]

In one word NO.

The boat came with MR 3 blade cleavers, and I had one throw a blade after 15 hours. It took 60 days to get a replacement from MR. The first weekend after the replacement prop came, after 1 hour of use, the other side threw a blade, it had 16 hours on it. This time the replacement came in 24 hours. I knew it was time to find another prop vendor.

Unfortunately i think this is more common than not. Nice job on the testing and data collected. It will be a real plus for 30 Skater owners to draw off of. You have some serious time and money invested and should be congratulated for posting the info for all to see.:cheers:

[hydroo]

In one word NO.

The boat came with MR 3 blade cleavers, and I had one throw a blade after 15 hours. It took 60 days to get a replacement from MR. The first weekend after the replacement prop came, after 1 hour of use, the other side threw a blade, it had 16 hours on it. This time the replacement came in 24 hours. I knew it was time to find another prop vendor.

When the MR's threw the blades were the motors toed out a 1/4"?
Very interested in the answer.

[appsyscons]

When the MR's threw the blades were the motors toed out a 1/4"?
Very interested in the answer.


yes they were

[2scoops]

When the MR's threw the blades were the motors toed out a 1/4"?
Very interested in the answer.

Have you had a similar failure? I am very interested in your answer!

[hydroo]

Have you had a similar failure? I am very interested in your answer!

YES! Any toe in on my Skater 32 classic with 300 X motors would cause me to throw a blade within an hour. I always make sure I'm running 0 toe in or out. That was with MR 14.5 X 32 LAB cleavers.

[dreamboater]

Frank, I recently switched from 3 blades to 4 blades due to prop failure, gear cases issues, etc. I have noticed a lot of stern skidding with the 4 blades vs the 3 blades. I am turning in on a 28 Skater with twin 300 promax's. My diameter is 14 3/4 and the pitch is 34. These props have been worked as they came off of a SS race boat. It seems that I am not running much different top end numbers empty vs weighed down. However when empty, I notice the rear of the boat skidding. I am currently at 1 3/4" above the bottom and have run a best of 107.8 at 6100. Trying really hard to get the boat to 110 and trying to figure out if I should reduce pitch or diameter.

What are your thoughts on this?

[Lance Woodke]

Dreamboater, I run 15" Merc 4 blade cleavers in both 32" and 34". My props turn out and I don't have a problem with my stern sliding while turning. I have been told that turning the props out on a 28 reduces a little top end but makes the boat more stable.

[dreamboater]

Mine slides at the top end not in a turn. It doesnt slide dramatically but its enough to feel it. Its just really loose on the top end. Turning the props out should give the boat even more stern lift I would think. What is your setup? Motors and prop shaft height?

[Lance Woodke]

250xs's Motors bolted to the transom 1.25" above the bottom. my best speed 101 high 90's any day turning the props in lifts the stern making the boat flighty at speed from what I have read on this site and been told by people who have tried both setups

[jpf091959]

Great work everyone.
I have a 25' Motion and my 2010 300XS' w/Offshore mids and 1.62 SM, just arrived last week. I hope to pick them up this week. I have 3 blade MR 28's, 30's and 34's. I am going to sell the 28's and 30's.
The 34's are 15" I was considering cutting them down to 14 3/4" diameter. I also usually run 1/8" to 1/4" toe in. I will stop that. I pretty much always put the prop centerline at 1 1/2" above.

I bolt my motors directly to the transom, but have 5" setbacks. I don't run my boat hard but do want 100+ MPH everyday of the week.

Open to suggestions. Great board.

[Lance Woodke]

Just one question. Why weren't you at the S & F rally at Crescent Bar? You missed the best one in 5 years.

[dreamboater]

250xs's Motors bolted to the transom 1.25" above the bottom. my best speed 101 high 90's any day turning the props in lifts the stern making the boat flighty at speed from what I have read on this site and been told by people who have tried both setups

I have tried both quite extensively with my 3 blades and turning out with my 3 blades was slower, turned better, but got flighty in a straight line on top end. The 3 blades were worked 15x34's and really carried the bow....actually way more than I wanted. I am 1 3/4" above the bottom currently but have run 2 1/8" above the bottom with my 3 blades. I have yet to turn the 4 blades out but dont think thats my answer. I am thinking about lowering my motor height and maybe taking some pitch out.

[Tague]

250xs's Motors bolted to the transom 1.25" above the bottom. my best speed 101 high 90's any day turning the props in lifts the stern making the boat flighty at speed from what I have read on this site and been told by people who have tried both setups



Turning your props in pushes the stern down, turning out lifts the stern, the more blades the more stern lift, and the more rake the more stern lift.

[jpf091959]

I missed the NW rally because I was moving into my house. I wish I put it off so I could be there. I didn't make it to the river at all.

My new motors are just sitting at the marina waiting to be picked up. I hope I can get there this weekend.

i have checked out some the pictures and I wish I would have been there. I am glad to see all the performance boats show up.

Was that Banjo's Skater. Did Brandi make it. I have his old Motion. I love it, the thing is a little dated, but it just works great.

[time warp]

Was that Banjo's Skater. Did Brandi make it. I have his old Motion. I love it, the thing is a little dated, but it just works great.

Yes Banjo was there, he's been to them all,
No, Brandi wasn't there