# Repowered and not all that impressed...also GPS no big deal 1K later



## mdrobe2 (Oct 12, 2007)

I bought my 15 ft. Key West in 2009 from Emerald Coast Marine and have been thrilled with the hull, fit and finish, etc.I thought the 50 HP Yamaha was a bit anemic soI sold it and got a 70 horse. You can definitely feel the difference with the 70- it is louder, bigger, and much improved out of the hole. However, I was hoping for 45 to 50 MPH out of it, and I am at 37-38 measured with GPS. Only maybe 5 MPH faster. Shocked that 40 percent more power yields only 5 MPH after adding only 40 lbs. of weight. I am running a stainless Stilleto prop. Thoughts?

Also, Idropped about a grand on a Garmin 540S GPS. I liked it, but seriously, 1K? Maybe I just don't know how to use it yet?


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## Gump (Oct 4, 2007)

Mike,.. you might be able to get a different prop to get more speed. I have some numbers for your new GPS that are ideal for your type of fishing.


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## X-Shark (Oct 3, 2007)

Mike I saw your 'Lil Key West today. Even Tishann said that's the size boat for me. HaHa.



Your asking to much of the motor. That is very close to the same speed that my 162 Scout runs with a 90 Yamaha on it.



I like those Key West Skiffs. I've had the pleasure to work on a 17ftr in the past. They are well made. The wiring is fairly typical, just so so and always has room for improvement.


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## sealark (Sep 27, 2007)

You may just have a prop problem. Check with Kenny Mann at Emerald Coastand see what he says. You can go down to Accu Prop and ask there opinion. I repowered DOWN from a 175 to a 150 E-tec and after changing from a three blade to a four blade i actually increased my hole shot and top speed. The Key West manufacturer would be another place to ask on what size prop for your configuration.


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## Sequoiha (Sep 28, 2007)

Hey Mike,, if you remember I said you were only going to buy 1 prop from me,, if you dont like the prop, lets try another one,,, I told you we could do this till you were happy,,, give me a call and lets make this right,,,


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## Splittine (Nov 24, 2007)

> *X-Shark (11/15/2009)*Mike I saw your 'Lil Key West today. Even Tishann said that's the size boat for me. HaHa.
> 
> Your asking to much of the motor. That is very close to the same speed that my 162 Scout runs with a 90 Yamaha on it.


I agree, I sold a 17" Maverick that weighted about 200-300lbs less than yours with a F90 on it and was getting about 46 WOT out of her.


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## mdrobe2 (Oct 12, 2007)

I'd like to clarify that this is not a problem with Kenny or Emerald Coast Marine.I was just surprised I did not get more speed out of her. It may be the hull design, or it may be the prop. Kenny has worked hard for me the entire time I have had this boat. I don't view it as an issue he has to "make right" though it was nice of him to offer. He did say to try different props as long as I did not damage any, so I may try that. As I said, I definitely notice the bigger motor, and the hole shot is good. I agree it is may be foolish to look for 45 to 50 MPH on a 15 footer. Thanks everyone for your replies. I want to stress that I am proud of the boat and don't think I could have done better given I had to have something to fit in the garage. The hull is fantastic, with a good trailer and Yamaha 2 stroke power. She's rated for 80 HP with a 70 on her- that ought to do it.


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## Snagged Line (Sep 30, 2007)

Mike, This might not be a good comparson, but I repowered a 15' Boston Whaler Dauntlis hull and I stepped up from a 40HP motor to a 50HP motor. Although I improved the Holeshot, It really did not seem to effect my top end speed very much (never accuratly measured top end speed before the repower) What I Did Notice was when running loaded the boat performnce did not suffer as it did with the smaller motor.

If you ever had performance issues when loaded to weight limits, try loading the hull down now and I would think this is when you will truly apreciate the added power. I would still play around with the prop until it is matched to what you now have...................Good luck.


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## wld1985 (Oct 2, 2007)

I've got a 17ft mckee craft, and it has a big 150 on the back of it... I dont remember what the speed is but, I would say around 40ish.. ITs no speed demon with that motor but it does cruise good and has a decent hole shot.


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## BudYsr (Oct 1, 2007)

My 17ft KW does around 40 with a 90hp, so I would think that you are right in line with the 70. That is flying in a small boat, plenty of speed, IMO. What rpm are you able to trim all the way up to and hit? 

The stilettos are badass props...


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## mdrobe2 (Oct 12, 2007)

BudYser- I think I was turning around 5300 RPM if I recall correctly...

Also, what is your 17 rated for?


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## BudYsr (Oct 1, 2007)

Mine is rated for 115 max hp, but the 90 is by far the most common engine used on the 1720 KW. I would have to guess that the 70 is right for the 15. Sounds like you are in the zone with your prop at 5300, but Im not sure what the max rpm is for your motor. I think you want to prop it to hit right at or very close to max rpm FULLY TRIMMED up and with a moderate load on the boat. As you probably already know, hole shot and top end speed are trade-offs with prop sizing.


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## Mullethead (Oct 4, 2007)

The Performance bulletin at the KW web site for the 1520 CCwith 50 hp 4S Yam (233 lb motor) shows a top end of 35 mph - 

Stepping up to 70 I would expect at most may get you up around 40 - ish - good luck and let us know how it turns out


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## sealark (Sep 27, 2007)

You need to figure your % of propeller slip and possibly go to a 4 blade prop. Here is a websight to do just that. If you can get the slip down to around 10% you should have a fast and economical ride. Like Kenny Mann stated he will work with you until you have the correct setup on your rig.









http://www.rbbi.com/folders/prop/propcalc.htm


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## Fishermon (Oct 19, 2007)

""<<Also, Idropped about a grand on a Garmin 540S GPS. I liked it, but seriously, 1K? Maybe I just don't know how to use it yet?>>""

Check for updates on the Garmin website..make sure u are running the latest software version 5.2. Also, you want to read and watch some videosabout the unit (545s), same unit but w/higher screen resolution, by "bluewaterpirate" from the hullthruth. Here is a link..

http://www.thehulltruth.com/marine-electronics-forum/181538-attention-garmin-owners-400-500-4000-5000-series-cps.html

at the bottom of the page check all other related 540s threads, itmay help some. Good luck, you have one of the best GPS units out there...


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## markm0369 (Oct 31, 2007)

At 5300 rpms sounds a bit low, dont know the redine for that motor, but should do a bit more, drop some pitch, I think 50 is pretty unrealistic, had a 15 ft boat with an 85that I could trim up pretty well in calm water and on a good day could hit 46, and the boat was pretty squirly . not much more in the water than the fin on the motor


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## FL_Panhandler (Oct 9, 2007)

Check the Yamaha website for performance bulletins (boat / motor tests) and look for boats similar to yours. 2 tests that catch my eye are the 17' Sundance Flicker with a 2-stroke 50 & a 2-stroke 70. It's a flats boat that weighs about 75 lbs less than a Key West 15, is a few inches narrower, but has the same deadrise. They got 36mph with the 50 & 39mph with the 70. My guess is you're close to dialed in because the Key West 15 is fairly heavy for a 15 footer at 950lbs. And it's pretty wide too. 

You may see small improvements with a prop change. Something to letyou getmore rpms (Wide open on the 70 is 5000-6000 by the way.) You may see a couple hundred more full throttle RPM's out of the motor all by itself as it breaks in more. And you might possibly be able to raise the motor on the transom. The mfg's usually tell you to set the cavitation plate a little below the bottom of the hull but you can often set it levelwith the bottom and go a little faster. As long as you don't blow out in a turn. There might be 3 or 4 more mph to be had if youget everything dialed in just so.


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## SCUBA Junkie (Oct 2, 2007)

Back in "The Day", and rule of thumb was: If you double your horsepower, you could expect to see a 50% increase in top end speed, so by my crude calculations, you increased your horsepower by 40% and saw a 20% increase in top end, which seems to run in line with the old standard. I bet with a 100 hp, you would see 50+, but I bet you can stay out all day on a few gallons of gas.


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## mdrobe2 (Oct 12, 2007)

I'd like to thank all of you for the info. I have been out of town and just got to read all the posts. I will have more to say once I do a little homework, but in the mean time I have a great little boat and can't wait to go fishing!


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## X-Shark (Oct 3, 2007)

> The mfg's usually tell you to set the cavitation plate a little below the bottom of the hull but you can often set it level with the bottom




Actually most run better with the cavitation plate 1in higher than the bottom of the boat when they are mounted on the transom as in this case.



But.....I bet that is the way Kenny set it up to begin with.


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## choppedliver (Apr 4, 2009)

I have an older 17ft with a 100hp johnson and it does 38-40mph WOT if it helps


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## eddy2419 (Oct 28, 2007)

FIRST make sure the motor height is optimal. Try raising it a hole and see what happens. Some cavitation at times is normal such as a high speed sharp turn. Be sure th e height is correct before doing anything else. The rules of thumb for motor height are all just starting points.


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## Sequoiha (Sep 28, 2007)

> *eddy2419 (12/12/2009)*FIRST make sure the motor height is optimal. Try raising it a hole and see what happens. Some cavitation at times is normal such as a high speed sharp turn. Be sure th e height is correct before doing anything else. The rules of thumb for motor height are all just starting points.


The motor height is fine,,,


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## eddy2419 (Oct 28, 2007)

edit, never mind.


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