FS18 speeds with 20hp

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seaslug
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FS18 speeds with 20hp

Post by seaslug » Fri Sep 02, 2016 2:08 pm

I finished my boat a few months ago and I seem to recall other builders getting 30+ mph with their boats and was wondering if anyone has an FS18 with a 20hp and what is the top end speed. I have a new 20hp Mercury with the stock aluminum prop and my top end is 26mph, and cruise at around 21-23 at 3/4 throttle. Do these speeds seem about right, and will a different prop give me more speed? Thanks, Mike...... Also posted a load of pictures of the build in the Gallery, under Mike's FS18 build, but having trouble downloading my most recent pics. Eventually.



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Re: FS18 speeds with 20hp

Post by jacquesmm » Fri Sep 02, 2016 2:42 pm

Tom likes to calculate props. It may be possible to get a couple extra mph out of that new 20HP. Maybe same prop specs but SS?
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Cracker Larry
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Re: FS18 speeds with 20hp

Post by Cracker Larry » Fri Sep 02, 2016 3:23 pm

I have a new 20hp Mercury with the stock aluminum prop and my top end is 26mph, and cruise at around 21-23 at 3/4 throttle. Do these speeds seem about right, and will a different prop give me more speed?
Yes to question 1. I doubt it to question 2. That sounds real good. Do you have a tachometer? What is your rpm at full throttle :?:
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Re: FS18 speeds with 20hp

Post by TomW1 » Fri Sep 02, 2016 6:55 pm

Your speed is going to depend on how much weight you have when loaded. Larry asked what your top rpms are at full throttle, we will need to know that also. Finally what is your current prop diameter and pitch. It should be something like 10 diameter x 12 pitch or 9 x 13 something like that.
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seaslug
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Re: FS18 speeds with 20hp

Post by seaslug » Fri Sep 02, 2016 9:48 pm

Thanks for the prompt replies guys. The stock prop has 10p stamped on the side, and it measures 10" in diameter. Running alone with rods, a light cooler, 5 gallons fuel, one of those tiny batteries, I get 26 WOT, and with another guy the same weight 170 lbs. I'm getting 24mph. I'm not that concerned with getting more speed, just curious if this was normal for the boat and a 20 hp. and whether a different prop, jack plate, or trim tabs would make any difference. I don't have a tack at this time so unfortunately cannot provide that info....Larry, sorry to hear about you experiencing some sort of health issues. You're always a great source of information and inspiration to all the builders out there, and was hoping to meet you in Homosassa in October. I'm not listed as a participant, but intend on making the trip.... I still can't figure out how to post pics on the forum, but managed to load a ton of pics to the Builders Gallery under Album Title; mike's FS18 build. I would appreciate any feedback, comments etc. and will also answer questions if anyone is interested in knowing anything about the build process. Thanks again, Mike

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Re: FS18 speeds with 20hp

Post by Cracker Larry » Sat Sep 03, 2016 7:50 am

Just go to your gallery, open the picture full size, right click on it and select "Copy IMG Location" Then go to the post where you want it, put your cursor there, then riht click again and select "Paste", or just type CTL V to paste. Then highlight the link and click on the box above that says IMG. It sounds harder than it is. Here are a couple of yours...

Image

Image

Image

Nice looking boat! Nice looking location too! Looks like home to me 8) Glossie Black would be jealous of your oysters :lol:

I think the speeds you are getting are very good for 20 hp. The one I built, my client put a 40 hp on 8O
Larry, sorry to hear about you experiencing some sort of health issues
Thank you. I've been real lucky over the years, been riding a nice big wave for a very long time. But every wave eventually hits a shore, and I can hear the breakers on the beach ahead.
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Re: FS18 speeds with 20hp

Post by RCC-SKIFFS » Sat Sep 03, 2016 9:33 am

Killer work Seaslug! I recall you said you were Flagler beach area?

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Re: FS18 speeds with 20hp

Post by Jeff » Sat Sep 03, 2016 11:13 am

Really nice looking FS18!! Jeff

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Re: FS18 speeds with 20hp

Post by seaslug » Sat Sep 03, 2016 2:34 pm

Thanks for the compliments guys. And thanks for the feedback on hull speed, nd I can't imagine why anyone would want a 40hp motor on this skiff. Guess I'm not in as much of a hurry, and my runs to where I mostly fish are very short. Those Oyster bars, and there are a lot, are just north of Matansas inlet, around Devils Elbow, 10 miles south of St. Augustine. Most of the Oysters in Flagler Beach where I live have died off probably due to all the development, silting from all the big boat traffic, and being a long way from an inlet with better water flow..... Larry, thanks for the instructions, still couldn't manage, just a dumb old carpenter in need of some tutoring to bring me into this century.....Would it be ok if I sent some pictures to the order desk email address? Will that work? Thanks again, Mike

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Re: FS18 speeds with 20hp

Post by Jeff » Sat Sep 03, 2016 3:44 pm

Mike, send your photos to the order desk or email them to me and I will get them up on your thread!! jeff@e-boat.net
Jeff

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