FS14 -The Ana Marie

[OrangeQuest]

Okay OrangeQuest lets get started again. You mention that you want to get a prop that just gets to the rev limiter, on the Suzuki's that is about 2000rpms above the stated operating range of 6000rpms. So now we are looking move the rpm range from 5500 to 6200 or 700rpms. So we have to reduce either the diameter or the pitch or both. So, looking at your factory prop of 11.25 x 10 we need to go down either in diameter or pitch. An inch in decrease in diameter is the same as reducing pitch by about 2.5 inches. A decrease in pitch increases rpms by about 200rpms per inch.

I have found a Michigan Match prop that should get you up close to 6000rpms. https://www.boatpropellerwarehouse.com/ ... ler-062208 Michigan Match are well known and have excellent reputations; you can read the reviews. It is a little more expensive but only about $40 or so, hopefully can fit your budget. Don't know if shipping is included by this vendor. You maybe can find one that does include it, or you have a dealer nearby.

As far as the 4-blade I am also having trouble finding one to fit your DF25A. The best I can find is a Michigan Vortex 11.5 x 8 which leaves your rpms about the same as you have. But you gain the advantages of the 4-blade. https://www.boatpropellerwarehouse.com/ ... ler-992401 The disadvantage I see is that buy the hub for your motor also.


Please ask if you have any questions.

Tom

Tom W I looked at the Vortex props and I am a little skeptical getting a prop that fits such a wide range of HP. And the ordering of a special hub insert. My old boat with a type 1 outdrive, I spin a hub and could take the prop to the local prop shop and get a new boot put in almost while I wait. I found a prop shop just a few minutes from me and has been in the prop repair business since 1958. Thank you for your efforts.

Solas makes a 4 blade for the Suzuki. I didn't check the availability. They list 11" thru 15" and 10" diameter.

I have a Solas 4 blade on my Suzuki V-Twin 25HP. No problems with the prop.

I see they do make a 4 blade and it is the close to the same pitch as my OEM prop and is less than $100.00 for the prop with free shipping. One of the reasons I bought the 25HP is they are now a 3 cyl and oh so quiet. And with full electronic engine control with no battery starting.

What I am thinking of doing is getting the 9" 3 blade prop and the 11" four blade prop and taking them to a prop shop not far from me and have them "blueprinted" and see what magic they can do to them.

From what I am reading on props, they can start out with less pitch near the hub and pitch increases as it gets closer to the tips. That could be some of the magic and mystery of props.
Getting two props for less than $200.00 would give me a few options for the adventures my boat will see.

[bklake]

My local prop shop said maybe, kinda, sorta, 1 inch pitch change on this size prop.

I wish I could help more on pitch selection but the boat I had this on was a Carolina Skiff J-14 and not the best at high speed. I never spent much time exploring RPM at top speed because it was scary up there. I think my V-Twin 25 tops out at 5300 RPM and it would get there at 23-25 MPH. Pulled like a freight train from idle to cruise speed.

I just looked and it is a 12" pitch. I think the stock 3 blade is 13" or 14" pitch. Odd that the pitch would drop that much on the same HP, same manufacturer. The DF-25 V-Twin is known for ridiculous torque.

[OrangeQuest]

My local prop shop said maybe, kinda, sorta, 1 inch pitch change on this size prop.

I wish I could help more on pitch selection but the boat I had this on was a Carolina Skiff J-14 and not the best at high speed. I never spent much time exploring RPM at top speed because it was scary up there. I think my V-Twin 25 tops out at 5300 RPM and it would get there at 23-25 MPH. Pulled like a freight train from idle to cruise speed.

I just looked and it is a 12" pitch. I think the stock 3 blade is 13" or 14" pitch. Odd that the pitch would drop that much on the same HP, same manufacturer. The DF-25 V-Twin is known for ridiculous torque.

I would guess it has a longer stoke and bigger bore cylinders to produce the same HP as a 3cyl.

Like Tom W stated, I need to drop 2 pitch sizes to get the rpms up. And I am a heavy boat

[TomW1]

What you are talking about is variable pitch and is beneficial for some props but not on all. If you have a good prop shop, go for it and have them reduce the 3-blade pitch 2-3". For the 4-blade reduce the pitch by 3" if tut hey can. They should be able to do at least 2" on an aluminum prop. But talk to them and see what they can do for you. Sometimes this is cost effective sometimes it is not.

Tom

[OrangeQuest]

Tom W:
There was a story posted on the Suzuki forum about a guy took his Solas 10.5 X 11 for his 2021 DF25A Suzuki.. Here is part of the story. He never updated his results after the prop shop visit.

Spoke with him this morning. He said he measured both props and found that the Suzuki prop has Pitch progressing from 11 to 12, while the Solas prop has pitch progressing from 9 to 11 on two of the blades, and 9 to 10 or 10.5 on the third blade. Says the Solas prop has a slight Cup on it, but not much. He feels that the biggest difference between the two props is the Rake. Suzuki Rake is 11-deg, while the Solas prop has only 7-deg Rake. He feels that the additional Rake is allowing the Suzuki prop to lift my light hull further out of the water and hence the additional speed. Frankly, this concept as I understood it from him makes no sense to me. He's planning to add Rake to the Solas prop and add a bit of additional Cup as well as try to tweak the Pitch on the weak blade (though he said that's really not a problem.) Promises I'll have it back by the weekend...

I am going to get the Solas 10.2X11 four blade and the 11X9 three blade. and see what results I get, then take them to the prop shop if I am not happy with the results. The OEM prop is performing very good for just putting around and my mileage has been great and so no work is needed on it. But I need a spare prop and then maybe a good heavy load prop too.

Will be hitting the lake again today then there will be a 2 week break due to work and spring break here in Houston. Then planning a fishing trip to the coast!!

[TomW1]

Okay get the two props and we will see what adjustments need to made to them after you get them and tested them. Tom

[bklake]

There are calculators out there that will give you your theoretical top speed based on prop pitch, %slip, and RPM. With my new Suzuki 9.9 and the 7' pitch prop, I am only going to see 16-18 MPH if I get it to max RPM. With a number that low, it feels better to use MPH vs. knots. The prop that came in the box was a high thrust prop suitable for sailboat duty. It was pretty easy to get max revs but the boat only goes about 8 MPH, consistent with the calculator I found. I'm over pitched with a 7" Solas but I knew that. I plan to swap out the computer and take out the restricter plate this spring. Don't tell anyone.

I put just over 7 hours on the motor doing break-in stuff. Not much high RPM running. The gas tank was feeling light so I filled it. Less than 2 gallons for 7 hours of running time. I swear these Suzukis use small eye droppers to meter the fuel.

Found it: https://goodcalculators.com/boat-prop-calculator/ Delete what is in the speed box and it will calculate it.

[OrangeQuest]

The fuel milage I am getting makes me forget to check the fuel level! seems the milage improves the more hours my motor has on it. Looked two or three times at the gauge and didn't seem to be moving. I think I used 2 gallons in 4 to 5 hours of just riding around.

It was windy, choppy and more boat traffic with a few bigger boats. seen a few ski boats and wasn't long the skiers were out. Even had a few swimmers on a sandbar. Was thinking, must be from up north, water temp was 67 degrees. But with all the extra waves and stiff wind, had a lot of fun and more testing of the boat. Hit a few waves that brought spray over the spray shield. And it was cold! After getting toasted, I called it a day. Dock traffic also picked up and needed to spend more time at the ramp so Ana Marie can get a few more compliments. She doesn't seem to mind the attention and she make me proud.

I found a defective switch that I have to replace. It's my anchor/running light switch. Already have a replacement, slightly bigger. So will need to cut a hole for it.

[TomW1]

bklake I have been propping boats to motors here for the last 15 years. Last year I did 11 boats of various lengths and weight. Your calculator is totally inadequate as prop slip depends on the prop, 10% is very high for a SS prop. prop slip can range from 4% for a ss prop to 16-18% for an aluminum prop. My prop calculations need motor specs, boat weight as it leaves the dock and design components It is 5 pages long to get to get to a 4-blade prop., the first 3 are the most important.

Tom

[bklake]

I wouldn't call it "my" calculator. It's just something I found on the internet.

Most everything I read on propping a motor involves adjusting the size and pitch to get the motor to the factory RPM spec. Tom W is the master at picking the right prop based on factors that most prop calculators don't account for. I found this calculator useful because I didn't know what I should see for speed when I got to max rpm. Or, I can get to max RPM but I want to cruise at 4500 RPM, how fast should I be going at 4500 RPM? I'm pretty sure it just calculates the forward movement per rotation of prop. All the inputs like gear ratio, RPM, slip ensure that you get to the proper forward advance per 1 turn of the prop. It's just a tool in my tool box that I can use real time to check my work. I could calculate the slip by leaving that input blank and putting in the other numbers. That would tell me if my chosen prop is a dud or good to go. I could take the prop to my local prop shop and tell them I'm getting x% slip at WOT, is there anything they can do to improve this? That would be far more useful information than "it ain't going fast enough, fix it".