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#1
08-03-2015, 07:46 AM
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YAPQ- Yet Another Propping Question
I did some searching around and some testing and I have some results and some thoughts I'd like to throw out to the Seacraft Hive mind.
I have a 1975 18SF, which is pretty stock except for: fuel tank moved forward, batteries under the console, console itself moved forward about 6-8 inches. Fuel tank is under deck 32 gallon. Motor is 1998 Mercury 2 Stroke ELPTO 115 HP, 20 inch shaft (runs really good. Well maintained) Motor is mounted 2nd hole from the top, but av plate was pretty much in line with the hull when I mounted it. Prop is a Michigan Wheel 13.25x17 aluminum. With me (230 lbs.) the wife (125 lbs.) full tank of gas (~200 lbs.) Plus some beach junk and enough food for a 230 pound guy, I feel like the motor is straining really, really hard to get the boat up on plane. Almost feels like I'm dragging some dead weight. Need to nail it up to almost 5000 RPM to get up on plane, takes about 5-10 seconds, levels off and cruises on plane happiest at about 19 kts at 4200 RPMs. Yesterday it was nice an calm in Wellfleet Harbor so I did a full throttle test. 5400 RPMS and 27.4 kts (gps) Looking over the stern, the AV plate on the motor is buried. Shell fall off plane at 16 and below. My thoughts are maybe the motor should be raised a hole or two? Propping thoughts? I thought 13.25x17 would be just about perfect. I have a stainless semi-cleaver style I was going to try thats 13x17. Maybe a little stern lifting will help? Any thoughts, observations or opinions? Thanks!
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Zachary [SIGPIC][/SIGPIC] 
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#2
08-03-2015, 08:59 AM
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Well Zach, After much deep thought you may want to consider
going on a diet...  Your wife will be happier and so willyour strained 115 Merc..  OK, I had my fun.. Add trim tabs first, they will help alot ! Hopefully the prop Gods will chime in.. I have never been real good trying to figure out what prop was best !
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See ya, Ken ©
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#5
08-03-2015, 05:24 PM
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Quote:
. .. ... Ok, not a chance. Guess I need a bigger motor/boat/cooler/swimsuit.
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Zachary [SIGPIC][/SIGPIC]
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#6
08-03-2015, 08:10 PM
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Broken record here:
Solas Amita 4. 15" pitch. 4 blade, aluminum. I get 27 knots on a Yamaha F100 with hydroshield and t-top on a Master Angler 20 with a kicker. I have a 2.31:1 lower unit. I would think you would like the hole shot, stern lift and top end. I have a 17P, and a 15P. I run the 15P. The 17 is a backup. Slightly better MPG, crappy hole shot. Slightly slower by less than a knot. Edit: with the hydroshield and stern lifting prop, and no t-top I can stay on plane at 10.5 knots. With T-top, I plane at 12 knots.
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#7
08-03-2015, 08:55 PM
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Quote:
You can also go to full powah in a jif. Ports we may not have seen. What are your slip numbers wot?
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#8
08-03-2015, 09:53 PM
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I have a solas 14.75 x 15 pitch if your interested. I also have a stilleto bay pro III in stainless which is also 15 pitch. Both props are lightly used, my 1994 mercury 150xl 2.0 revs up past 6000 rpms with both props. I now run a mercury mirage 17" pitch and still get to 5800 rpm, i might need to buy new hub for mirage prop seems like its slipping at WOT. I'm in southeast MA let me know if your interested.
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http://s1103.photobucket.com/albums/...acraft%2020SF/
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#9
08-03-2015, 09:57 PM
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Quote:
You have to be a little thick skinned to put up with this chit... I'm in the same boat as you, me 210 lbs, wife 115 lbs.... Why do you think I have 200 ponnies on the back of bones.. And yes, I need bigger swim trunks too.
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See ya, Ken ©
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#10
08-03-2015, 10:14 PM
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Just found this thread this on scream and fly
http://www.screamandfly.com/showthre...merc-115-elpto I still think you would benefit from a 4 blade with a 15" pitch. Your welcome to try the ones I have.
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http://s1103.photobucket.com/albums/...acraft%2020SF/
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