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Hello! Getting 28 mph @ 5500 with my healthy and properly trimmed Suzuki DF 40. Motor is rated at 5200-5800 wot. The prop it came with is 11 5/8 x 12 and I'm at 6200 WOT with this set up. Thinking of pitching up to 15 to bring it down to 5600ish, or 14 for 5800 and get the 35-40 mph I'm hearing about. Which one, 14 or 15? What should the diameter be? In 15 and 14 pitch there is everything from 10-11.5 available. Any insight is much appreciated.

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The diameter is a given and selected by the engineer.

We can only choose brand/model of prop for our particular motor and then the pitch size.
See this article:
http://www.whalercentral.com/articles...cle_id=108

So, forget about diameter as this is already figured out for us.

What brand/model of 12" pitch prop do you have now?

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If you actually have a 1973 model, then you should have a 20" Long shaft motor and the straight transom with Desert Tan interior.
See this Frequently Asked Question:
http://www.whalercentral.com/viewpage...age_id=155

Other things to check is your engine height.
What holes are the engine bracket bolts in?
http://www.whalercentral.com/articles...cle_id=106

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Right on. It's a 73 for sure same as in your link. It's a 20inch and the gear is 2.26 I believe. As far as the diameter that's what I thought too but shopping for props by motor I'm finding everything from 10-11.5. Hmm. That is for different brands though, so maybe that's part of the design for that particular prop? The prop on it does not give a brand but I'm pretty sure it's stock as the motor had under ten hours when I got it, and it showed. I'm looking for max speed as the fishing spots I love are 10 miles away plus. Getting out of the hole fast is fun but I'm not that worried about it.

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Not in the same brand/model of prop you aren't......
If you do see this, please give us a link.

Every brand/model is made differently and has different engineers designing the prop for a particular motor.

Choose one brand/model for your motor....
Like the article says, you won't have a choice in diameter...

Here is what you will see if you choose the "Viper" brand/model for 40hp to 130hp E-Tec....
763929 ViperTM 3 blade 13 7/8" x 15 pitch
763930 ViperTM 3 blade 13 7/8" x 17 pitch
763931 ViperTM 3 blade 13 7/8" x 19 pitch
763932 ViperTM 3 blade 13 7/8" x 21 pitch

Again, we have no choice in diameter..... Only the pitch.....

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I haven't seen a single brand with a choice in diameter like you're saying. That said, when I go up in pitch should I pick a brand that has close to the same 11 5/8 diameter or not worry about it. If I go stainless it's a bit of money to gamble as it's seems there's a quite a difference between 10-11.5. Probably more important for me
is 14 or 15 pitch.

Thanks for the quick replies and nice site by the way

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On of the ways you decide what model of propeller to use is to see what its diameter is. Diameter is one part of the overall composition of a propeller.

A Suzuki DF40 is not going to have a lot of choices. It uses a 3-1/2" (small) hub.

Let's consider the options. The Suzuki propeller catalog only offers two models of propellers for the DF40, an aluminum three blade in pitches from 7" to 17" and a stainless steel three blade in pitches form 12" to 17". That's it. You don't want an aluminum prop if you are concerned about your boat's performance or else you wouldn't have started this thread.

If the prop you have now is a Suzuki prop and it's 11-5/8" x 12" then it the aluminum three blade, part #58100-88L31-019. I suggest upgrading to stainless steel to help solve your problem.

So that leaves their thee blade stainless steel prop (*if* you want a Suzuki branded propeller) and all you have to do is decide the right pitch. If a Sport 13 can do 35-38 MPh with 40 HP and the DF40 uses a 2.27:1 gear ratio and has a 5800 RPM redline then you will want at least a 15" pitch prop. The Suzuki three blade stainless steel model would then be their 11-3/4" x 15", part #990C0-00501-15P

I actually think you would do better controlling the bow rise by using a prop with better stern lift qualities, and a large diameter prop with less rake will help accomplish that. The Stiletto Star 3.5 is one such prop and you can get a 12" x 15" version with a C-011 hub kit to fit your DF40. It will cost considerably less than the Suzuki branded stainless steel propeller too.

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OK. So you do have an aluminum prop....

I would suggest a SS definitely.
Many prop shops will loan you a brand/model of prop to try out in different pitch sizes before buying....

It's been too long since I owned a 13' so I do not know the best brand/model.
Tom, and others here that have 13' models, might be able to recommend the correct brand/model and pitch for you.

The engineers of the prop calculate the Rake, Cup, and Diameter for a certain motor(s) so basically the only choice we have in that brand/model of prop is Pitch.....

If you take a look at that article again, each 2" pitch change can raise or lower the WOT RPM by about 200 RPM.
If you were to stay with the same brand/model you have now, then you would want more of a pitch.

You don't mention the year of your Suzuki DF40
Here is a chart for Suzuki propellers.
http://www.suzukimarine.com/~/media/M...s_PDF.ashx

NOTE: the SS props for a DF40, 1999 to present
They all have the same diameter of 11 3/4 inches but that isn't always the case. Sometimes the diameter varies but again, we have no choice in diameter in a particular brand/model...
Stainless Steel 11-3/4 x 12
Stainless Steel 11-3/4 x 13
Stainless Steel 11-3/4 x 14
Stainless Steel 11-3/4 x 15
Stainless Steel 11-3/4 x 16
Stainless Steel 11-3/4 x 17

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Rock on. Thanks for the time. Being Monday I'll get on the horn with some prop guys, I live two hours from most but no biggy. The Stilleto Star says designed for pontoons, I assume mostly because of the diameter amongst other things but you think that may be a good one. I was looking also at the Stilleto Triad with a 10 3/4 as I don't think I'm having much problem with slip with the big motor and all. I also have a small Doyle fin on there and with that don't get any bow rise or porposing, although I know it's a cover up so maybe your suggestion is a good one the 12/15 Star Tom. No go on the Suzuki SS, out of my price range, although seems like a no brainer. I'll make some calls and check back. much thanks

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Yes, the Star is nominally a pontoon boat propeller except it also works on other types of boats too. Here is what the manufacturer wrote about the Star's sibling, the Yamaha branded Pontoon Performance Series version:

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Called a couple prop shops today and got some decent but kind of generic info. Actually one person tried to tell me I needed a smaller pitch to get the rpms down. Going on to the beach for a few days in San Diego. May swing by a shop there. Thanks for the info again. I'll check back when in a few to follow up. Cheers

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Feel fee to keep talking to "shops" but you've already found the world's best source of prop information for Whalers right here.

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AZ, you're going to get "a range" of advice from shops, for sure. But don't buy a prop at a shop unless you like spending extra money. The Star 1 + hubkit can be found online for approximately $235 delivered to your door.

Tim

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I am running a 15 pitch prop on a 73 13 sport with a 40hp Yamaha. I get 38 mph when trimmed out. the best cruising speed with this prop is 28-30mph anything over about 32 mph is not fun.

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Back from vacation. I manage a fleet of inspected vessels, I know how hard it is to get really good service, that's why I'm here for sure. Unless its a computer or cracking motors we do it ALL in house. I'm a jetpump guy and sailor so props aren't my game..yet. Tirermc, I know your yammy is different, but what model prop are you running(great motor by the way)? After doing my own research as well, almost ready to go for Tom's suggestion of the Star 1. Less rake, larger diameter= good for my set up. Question-Since I have alum now and my calculation says to go to 15 pitch, so would switching over to the stainless Star necessitate an adjustment in pitch because of the change in material? Also does anyone have any account of this prop being used on a 13 whaler? Also for giggles I just raised the motor up one hole to it's highest(VP 3/4" above keel line) and lost 3 mph and it seems to have slightly more bow rise.

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Another question on the Star. I read it has a fair amount of cup. My current prop seems to have little to none. Since, from what I'm reading, cup can have a similar effect as increasing pitch. For this reason would it change my pitch calculation from 15? Tell me if I'm splitting hairs. Thanks again!

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Rider,

I highly recommend you save yourself a lot of time and money and buy the propeller recommended by Tom Clark. Tom sells propellers, too, and his prices are more than reasonable.

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I might be misunderstanding your statement, but Prop Tech has a few models with different diameters. I only looked in the 40-70 HP range since I'm looking for a new one. See: http://www.ptprop.com/images/stories/...cclass.pdf and look for the following models: NREB3, OLC3, SRG3, they all vary diameter with pitch within that model.

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tmann45,

You need to look up the prop for your motor, then give us the props that show up.
That chart shows all the props they have. They all will not fit your motor.

Here is what you find when you look up a SS prop for a DF40, 1999 to present on the Suzuki site.
They all have the same diameter of 11 3/4 inches but that isn't always the case. Sometimes the diameter varies but again, we have no choice in diameter in a particular brand/model...
Stainless Steel 11-3/4 x 12
Stainless Steel 11-3/4 x 13
Stainless Steel 11-3/4 x 14
Stainless Steel 11-3/4 x 15
Stainless Steel 11-3/4 x 16
Stainless Steel 11-3/4 x 17

In other words, pick a brand/model of prop.
Look up what prop fits your motor.
Then give us that information.
I guarantee you that you will not be able to choose anything like this in the same brand/model prop for your motor:
11x17
11 1/4 x 17
11 1/2 x 17
11 3/4 x 17
etc.
Generally you will only be able choose the pitch for your motor in one brand/model prop.

Did you look further on that site above where you gave us the link?
If you had, then you would have seen they Do Not ask you anything about the diameter when asking you about your current prop. They only ask you about the pitch, number of blades and brand of prop of course.
http://www.ptprop.com/index.php?optio...;Itemid=60

The above is the exact same thing they would ask you in a good prop shop.
What motor you have, what brand/model of prop you think you want, and what pitch.
They might give you suggestions on brand/model and pitch for your particular boat and how you use it, but they won't ask you what diameter you want.

Custom Race props are not in the above category. You can have anything you want made to get the most out of your race engine and race boat hull.

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Joe, you have me confused with the another poster. I was only replying to your request for a link that shows a certain model prop that comes in different diameters.

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No, I don't have you confused.

You didn't show that at all. All that shows is props come in many diameters. They do.
However we don't have a choice.
You didn't show us what engine those were for. They certainly all weren't for your motor.

If anyone can show me they have a choice in diameter from the same brand/model prop for your particular engine, then show it.
I have showed many times that you cannot change the diameter or have a choice of diameter in any One brand/model of prop for your particular motor.

I will argue this with everyone until I am dead.
We cannot go into a prop shop and order a 14" diameter prop unless we make a lucky guess.
And then who knows what pitch that will be?

We have no control of the Rake, Cup, or Diameter of a certain brand/model prop we choose.
The engineers figure that out for our particular motor/gear case.
We choose a brand/model prop and then we choose the pitch we want.

What brand, year and size of motor do you have?
Let's try and find a prop for it and see.

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I think I'm going to order up the 15" Star prop. Would be nice to get first hand info of it's use on these boats, but hey what do you do. I'll check back in when I get it going for the curious and nautically obsessed. I will say I've learned a fair amount about props lately. On a side note, I used to live in KW and would hang out at the Offshore Worlds Championships. Those boats had some props.

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Stiletto Star ordered. $200 shipped with hub kit. Not too shabby.

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Let us know how the new 15" pitch prop works out for you.

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Will do for sure. Should be here Monday.

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OK, got the 15" Star installed and test drove today. Getting about 4mph more at given rpm, but WOT is now only 5100. Enough vibration at low and mid rpms that I'm not going to run it for fear of engine damage. Installed w/ Stiletto Guardian hub. It was silky smooth with the stock prop. Anyone?

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What was your average top speed at 5100 RPM, as measured with a GPS and a two-way test run?

You probably should have chosen the 14" Star to gain some engine speed at WOT. Exchange the 15" for a 14" and try it again. That will rule out (or confirm) the propeller being the cause of the vibration.

How was the bow behaving?

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No returns on used props @ iboats.com. Seems like it would be nice if the hub had some rubber and not just delrin or what ever, especially for an ss prop. Also has a much harder thunk when going into gear. Top speed @ 5100 was 33 mph. That should go back up a few mph when I lower the motor back down a hole. Maybe a little less bow movement but not enough to matter as it wasn't bad with the stock prop, does plane at lower speed though. If it wasn't for the vibration I'd be happy enough. Annoyed though that this prop changes rpm almost 400 per inch of pitch though. How is anyone supposed to buy the right one? Thinking about calling Stilleto on Monday on that. In the mean time will reinstall to try to get the vibes out. What rpm should I run it at so I don't overload this thing?

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Oh, you bought a used prop from iboats.com. That explains the low price. It might also explain the vibration if it has been bent.

How much the engine speed changes with a pitch change depends on the gear ratio of the motor, and to a lesser degree, how much pitch you start with. It doesn't have anything to do with the brand of propeller, it's just simple arithmetic. A DF40 has a 2.27:1 gear ratio and in the low pitches your boat might make use of, one inch is a relatively large percentage change. One inch is going to inversely relate to 350-400 RPM for you.

There is no question but that stainless steel propellers, which weigh more, have more shift clunk. That is why Mercury, who pioneered the field replaceable hub kits with their Delrin inserts, also offer clunk dampening hub kits like the Flo-Torq III and Flo-Torq IV. Other hub kits also soften shift clunk like Solas's Rubex hub kits. Unfortunately, I am unaware of any small gearcase sized hub kits that offer shift clunk dampening apart from Mercury's Flo-Torq Reflex which do not fit the Stiletto.

The recommended WOT operating range of the Suzuki DF40 is 5200-5800 RPM. I would try to prop your motor to hit the upper half of that range, ideally.

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New prop, sealed in box as far as I could tell. Went to reinstall and noticed a few things. First with the prop nut not torqued the Star has about an 1/8" of play at front or rear when moved side to side or up and down, some of which is in the prop/hub interface and some the hub/shaft. My stock prop has basically none. Even the machining of the hub/shaft faces are off a fair amount. Lightly torqued the Star still has some play as you can't torque the plastic "prop nut spacer" enough to get it to "button up". The stock prop came with a quality bronze spacer and was torqued to what felt like about 50lbs. You would destroy the cheesy plastic one doing that. And when I went to take it off from the test run it was much looser than i had tightened it, indicating that when running the plastic compresses loosening the whole thing. This system seems flawed to me. Next problem, after running it in fresh water Lake Mead for 3 hours the thing has a fair amount of surface rust and what even looks like the first signs of pitting. Having lived on boats for years in FL and the Caribbean I'm familiar with the qualities of ss. This thing wouldn't last a season in FL without having to buff it out and wax it every use. Bottom line, this thing is a dud in too many ways. Going for the return then ordering me up a Suzuki aluminum prop. I will say I'm not a big fan of ordering stuff like this online, but the iboats guys are local enough(for me), and had great service so far. I'm two hours from the closest prop shop so. We'll see what they say Monday.

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Apologies if this post is getting a little stale but I thought I'd follow up a bit. Told iboats about the issue and they politely offered up a return with full credit. I'll order through these guys again when needed for sure, the service is great and they're very friendly. As far as the prop goes I'm just going with an aluminum for the built in rubber and light weight, not to mention the price. I liked the performance on the Star prop and maybe I just got a bad one with the rust issue, and maybe the hub for Suzuki/Johnson just needs a little tweaking so it fits tighter.

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Good on iBoats for taking back the prop that did not work for you.

The discoloration you describe is normal and affects all brands of stainless steel propellers, though not all of the time. It depends on the chemical composition of the water the prop is used in and is not rust (oxidation). It is not a sign of low quality in any way. The propeller also could not have any pitting. Pitting is caused stray current corrosion in exceptionally "hot" marinas and even in severe cases takes several days or weeks to begin.

The difficulty you had in installing the hub kit was probably because you did not fully seat the hub insert in the propeller before installing on the motor. The instructions that come with the small Guardian SQ-Lok hub kits are very poor, in my opinion. They do not make this point clear and I have seen some that call for 55 foot/pounds of torque on the propeller nut. There is no reason on Earth for a small propeller to have that much torque on the nut, it will just crush the spacer.

I put the prop on a firm surface and drop the insert into the propeller then tap the insert down until it is FULLY SEATED. Then I slide the prop on the propeller shaft. This way, you are not relying on the propeller nut to tighten and compress everything together.

Older Stiletto Stars used a press-in rubber hub. Perhaps you can find one on Ebay. The next size down is 13" pitch; there is no 14" and that might be the perfect size. After all you gained 4 MPH when you switched to the Stiletto Star.