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Anyone running a 17” or 18” SWS II on a KW 239 with 250 HP?

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Anyone running a 17” or 18” SWS II on a KW 239 with 250 HP?

Old 03-15-2019, 04:30 PM
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Default Anyone running a 17” or 18” SWS II on a KW 239 with 250 HP?

I need to reprop to something smaller than my current 19” SWS II on my 2018 KW 239 FS with Yamaha 250... I’m fully trimmed, but only getting 5300-5400 rpm lightly loaded.

Anyone have same general setup with smaller prop?
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Old 03-15-2019, 06:48 PM
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A 17 SWS II should get you very close to 5800. Very good prop. Does very well with that motor. That motor shouldn't need anything less than a 17 pitch on that boat. Motor height correct?
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Old 03-15-2019, 07:30 PM
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Hi 28570,

Yes, correct hole per other 239 FS owners.

Have been collecting data from others with same boat and 250 ... almost all report similar rpm at wot, with a few doing a bit better with the 19”. Many same boat with 300s do better, assuming from the increased 25 or so horsepower.

Been looking for someone with same boat and motor and either a 17” or 18” SWS prop - lot of folks would switch props, but don’t want to experiment at $500 a shot.
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Old 03-15-2019, 07:37 PM
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Well those RPMS are to low. Need to be atleast 5800. Every pitch is usually 150 to 200 difference. 18 isn't getting you there. 17 should get you close enough.

The other props are Eco Enertia , Mirage Plus which is very close to the same as a SWS II.

The SWS II are made for the 4.2 L motors in general. Work very well. You need the right pitch

Your boat isn't that heavy. My SH BX 24 turned a 19 to 6000 easily.

17 should be very close.
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Old 03-16-2019, 03:28 PM
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I’m guessing you are fully loaded, ttop, bottom paint and trimmed out only getting those RPMs? Did you joint the KWB forum??? Quite a few posts about props for the 239 DFS/DF.... you might find that you can add a little cup to a 17” SWS II or maybe even 1/2” pitch.
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Old 03-16-2019, 03:40 PM
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From initial post - "I’m fully trimmed, but only getting 5300-5400 rpm lightly loaded."

Two people, 1/2 tank fuel, no water, T Top, 100 hours, no bottom paint, one anchor on the windlass. Saltwater, minimal wind (even downwind), trim to cavitation, then back off a click. Dual GPS.

I started the largest thread on this boat with this motor on keywestboats forum - almost no other props in use on 239FS on the keywestboats forum - or, at least that I've heard from. Apparently, the 300s and 250s all get the same prop - the 19" SWS. On some 300s owners report around 5800 RPM, but mostly less. Most 250 owners report around the same 5400, with a few up to 5700 rpm or so. Doesn't always make sense that the same prop would be used for both, especially given that the rpm on the 300s never gets any of them to 6000 rpm.

Loaded - three guys, ice, fishing gear, food and drink - I get around 5100-5200 rpm.

My dealer is a great guy and is sticking by our agreement to swap out props - and, he is trying to set up this combo and try and couple of props, but has been able to this cycle, yet. Someone, somewhere must have already done this ... if I was at a big boat storage place, I would be out looking at every 239/250 combo to find a 17" and an 18" ...then track owners down to see what their experience has been,
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Old 03-16-2019, 04:15 PM
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If you aren't in hole 3 move the motor up a hole. In 2016 I talked to a few new KW owners and that is where they started. Also the 18" seems to be where a lot of people should end up with the 4.2's. you can always try a prop from prop gods.
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Old 03-16-2019, 04:53 PM
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thanks, dave,

My dealer will swap out either a 17 or 18 for my 19" ... been a great guy - I think he wants to know the answer, as well, but doesn't have much time to mess around (small dealership).

Manufacturer's GM has confirmed the correct hole on it - KW is pretty darn good at maintaining the connection between the buyers and the company - see photo. I think this is the position you are talking about?

Using the "magic" 200 rpm/inch prop, an 18" on a loaded boat would still only give me 5300-5500 rpm ... 17" potentially 5500-5600 rpm. Starting with my current 5300-5400, 18" 5500-5600 and 17" 5700-5800.

I think the 17" is going to be the right prop, but it would be great to get real data from someone running one of those!

And, I would like to be able to make a POINT to the manufacturer that they are overcropping these boat/motor combos.

There is also a mysterious component - over the last 2 years the availability of 17" and 18" SWS props has been problematic ... a conspiracy theorist might ask whether this played a part in simply slapping 19" props on? :-)
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Old 04-12-2019, 08:56 AM
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Still looking for others with same boat/motor combo ...

Out yesterday - 5200-5300 RPM and 48 mph - way trimmed - just prior to obvious cavitation ... bit of headwind. 3/4 tank, two people, no tackle, no ice. Best cruise mpg was about 3150-3200 rpm, 28 mph or so, 3.5 mpg or so.

Every new KW 239 FS I have heard from is receiving 250 and 300 with 19" prop. 300 owners get a few more rpm - usually 5600 or so, probably due to additional HP (about 20-25 hp).

Anyone with a like boat/motor combo, please jump in, too ... KW 239 is pretty darn lightweight, so will have to consider that as well as hull, etc ... but, any data would be helpful on the 250 ... it's obviously overcropped for my boat, but I want to get enough data to push it back to Key West - assuming they didn't simply throw a 19" on it because the 17s and 18s weren't available (this is one continuing theory).
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Old 04-12-2019, 09:09 AM
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Years ago I had a 23' boat with a SWS 200 that came with the 19 prop. My RPM's were the same as yours. I switched to the 17 and my WOT was exactly at spec, and performed better as well.
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Old 04-12-2019, 09:28 AM
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Originally Posted by stephenson View Post
thanks, dave,

My dealer will swap out either a 17 or 18 for my 19" ... been a great guy - I think he wants to know the answer, as well, but doesn't have much time to mess around (small dealership).

Manufacturer's GM has confirmed the correct hole on it - KW is pretty darn good at maintaining the connection between the buyers and the company - see photo. I think this is the position you are talking about?

Using the "magic" 200 rpm/inch prop, an 18" on a loaded boat would still only give me 5300-5500 rpm ... 17" potentially 5500-5600 rpm. Starting with my current 5300-5400, 18" 5500-5600 and 17" 5700-5800.

I think the 17" is going to be the right prop, but it would be great to get real data from someone running one of those!

And, I would like to be able to make a POINT to the manufacturer that they are overcropping these boat/motor combos.

There is also a mysterious component - over the last 2 years the availability of 17" and 18" SWS props has been problematic ... a conspiracy theorist might ask whether this played a part in simply slapping 19" props on? :-)
Your pic never posted showing your outboard height. Hole 3 would be counting from the top.
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Old 04-12-2019, 10:09 AM
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OP may have just have a weak 250....
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Old 04-12-2019, 01:20 PM
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I am in the second hole the from the top - this is same place as all other KW 239 FS owners - factory position.

My experience in RPM and speed is the same as almost all other KW 239 FS owners with 250 Yamahas ... that is actually the key point.
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Old 04-12-2019, 03:15 PM
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OP: you have been perseverating over this since last summer. There is no question you are over-propped. Borrow an SWS II 17" prop from your dealer already and see what max RPMs you can get. if you aren't getting at least 5800 rpms fully loaded at WOT trimmed out then either you need to drop more in pitch OR you have another issue with your motor. Note that it is entirely possible that your current 19" pitch prop is "off." It does happen.....
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Old 04-12-2019, 03:39 PM
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Originally Posted by stephenson View Post
I am in the second hole the from the top - this is same place as all other KW 239 FS owners - factory position.

My experience in RPM and speed is the same as almost all other KW 239 FS owners with 250 Yamahas ... that is actually the key point.
you need to be in third hole from the top. That 9”set back that our boats have allows you to run the engine a bit higher. I am running a 250 on a 219FS, third hole, 19” 3 blade prop or an 18” 4 blade OFS prop and get 5900 rpm all day long. Heavy load.
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Old 04-12-2019, 04:00 PM
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The boat is a 239 not a 219 ...motor is same height all 239 Yamahas 250 and 300s are mounted.

My dealer is in another state - reportedly only recently were 17” SWS even available (part of the mystery of why 19” on 250s and 300s and no one experimenting with SWS replacements.

The point of collecting the data is ensure there is a sufficiently probable feedback mechanism to Key West to help other owners and dealers, etc select the right prop.
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Old 04-12-2019, 04:05 PM
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And, I would think perhaps it is my prop, except almost every 239 FS with a 250 Yamaha experiences same rpm issue.

Some have postulated the lack of 17 and 18” props may have contributed - perhaps boat manufacturers blindly following Yamaha guidance and Yamaha is saying use 19s because they don’t have 17s available?
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Old 04-12-2019, 04:06 PM
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Why do people pay $500 for these props? What is different than say a solas prop? Solas aluminum prop is $75. Hub kit is $25 . Cheap way to experiment.

Last edited by Cpfitness; 04-12-2019 at 04:46 PM.
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Old 04-12-2019, 04:11 PM
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Originally Posted by stephenson View Post
The boat is a 239 not a 219 ...motor is same height all 239 Yamahas 250 and 300s are mounted.

My dealer is in another state - reportedly only recently were 17” SWS even available (part of the mystery of why 19” on 250s and 300s and no one experimenting with SWS replacements.

The point of collecting the data is ensure there is a sufficiently probable feedback mechanism to Key West to help other owners and dealers, etc select the right prop.
I know yours is a 239, but we are talking 400 lbs difference only between the two boats. what is the concern against trying the engine mounted one hole higher to see where your AV plate settles and your rpm/wot combo look like?
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Old 04-12-2019, 04:40 PM
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You need a 17 pitch prop. Mirage Plus Merc is very similar to a SWS II. Power Tech makes a version of the SWS II. I ran a 19 on my BX 24 bayboat. The Yamaha gears these motors at 1.75. They very rarely will turn over a 19 pitch unless its a fast hull or light boat. 19 works on a lot of bayboats. But CC boats with a hardtop tend to be a 17 pitch.
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