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08-21-2019, 09:44 PM #1
Checkmate Pulse 186 Porpoising; Jackplate & Smart Tab?
Hello Everyone,
I've scoured the internet regarding porpoising on Checkmate Pulse boats, in my case, a 186 with a Mercruiser 175 Xri mounted to the transom. I have a stainless Stelleto 23p x 14" 3 blade prop (Advantage II series, 10323 m1423).
Right now I can do 58 mph @ 5600 RPM (WOT spec is 5500) with 3/4 tank of gas and 450 pounds of people. That's plenty fast for me. What I'm really after is the elimination of porpoising in the 30-40 mph range. I've considered Smart Tabs, and ultimately may end up with them regardless of whether I buy a jackplate or not. My cavitation plate is about 2" above the pad, and I've read that it should be at least 3" above, perhaps more. Prop centerline is 6" below the pad. I can trim as high as I want at speed without a blowout.
I'm considering a 10" Slidemaster manual jackplate mainly for adjust-ability, with the hope that it may help my porpoising, and the fringe benefit of more speed. Will the jackplate do much for the porpoising? Will simply raising the engine help? I can go up 3 holes right now.
The Pulse jumps out of the hole nicely. But I have considered an aluminum 4 blade prop, perhaps a Nemesis, for drive-train insurance reasons against rocks. I like going fast, but I don't need to wring every last MPH out of the boat. Will a prop like that also help with the porpoising?
Thanks in advance for all of your insights!
EDIT: Though there's not much mention of porpoising, this thread answers many questions about Pulse 185 and 186 setup: http://checkmate-boats.com/forums/sh...t=Pulse&page=3
GrantLast edited by Grant Conklin; 11-13-2019 at 10:28 PM.
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08-23-2019, 02:39 AM #2
are you running fairly neutral trim while it porpoises? can you eliminate the porpoise with negative trim? tabs will help but are not necessary IMO. A 10" jackplate will def help balance it out and help carry the bow. it'll likely gain you a few mph too. I know the 21's like 14-16" setback so 10" should be in the ball park for the 186. there is the possibility you might just be using to much positive trim at that speed.
in case anyone hasn't mentioned it make sure you are running a water psi gauge when you add a jackplate.
also I would not recommend the aluminum prop, not great for surface piercing and they wont give you any bow lift characteristics. if you are worried about rocks, the flo torque hubs are supposed to shear in the same fashion as an alu prop. I just try not to hit rocks lol.
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08-23-2019, 09:00 AM #3
Thanks derpid,
It seams to porpoise at any trim setting other than mostly negative, and I'm not running efficiently at that point. There is a psi gauge on the boat already.
Funny thing about rocks. I do 90% of my boating on the St. Croix River and have only nicked 1 rock there, and not in a way that affected my aluminum prop (on a different boat). On lakes, I've hit a few, in ways that ruined them.
Thanks for your help!
Grant
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08-24-2019, 09:20 PM #46000 RPM
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Possibly strake transition to slow to lift, so it falls back down.
Dose it bounce or if you leave it does in become out of control?
might try a synthetic wax to help it break free.
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08-25-2019, 05:47 PM #5
It's a very pronounced bounce, I don't know that I'd say it's out of control. Definitely makes you look like an amateur. I've been told that it's a common characteristic of the whole Pulse line up.
I initially asked my question on the Checkmate forum, but wasn't getting any responses. Now I have a few over there. It sounds like a 60 pound bag of sand in the tip of the bow is doing the trick for some. I plan to try that.
Also, I found this technical description of porpoising helpful: https://www.screamandfly.com/content...-How-To-Fix-It
Thanks,
Grant
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08-25-2019, 06:08 PM #6Screaming And Flying!
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Try a different rake prop?
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08-26-2019, 06:38 PM #7
Trophy's provide alot of lift, might allow you to raise your motor a couple holes, as long as you can pickup water.
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08-27-2019, 11:15 PM #8
Thanks FMP and Baker343. I'll be on the lookout for some props to try.
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08-27-2019, 11:22 PM #9
Out of all the props I’ve tried (which is almost everyone of the go to bow lifters) the best bow lift I found was with a solas scorpion, the trophy didn’t even come close. Not to say it won’t work for you, my boat is very nose heavy. If you do get ahold of a scorpion, test one 2* lower than what you currently run as they are cupped something fierce.
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Grant Conklin thanked for this post
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08-28-2019, 12:10 AM #10Screaming And Flying!
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Less rake, run level, raise the motor one hole. Let the hull work with a bit of trimming. Cheapest way forward and get a baseline of what it does.
.Last edited by FMP; 08-28-2019 at 12:17 AM.
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08-28-2019, 12:11 AM #11
Well now I'm curious. It looks like it now goes by the name "Rubex S3," or some combination of "Rubex Solas S3 Scorpion." Since I currently have a 23p prop that's spinning 100 rpm over the 5500 WOT spec, I should be looking at a 21p Scorpion, but it looks like the smallest is 23p. And there are no used ones on Ebay. I'll keep a lookout.
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08-28-2019, 02:34 AM #12
I forgot about the fact they start at 23 lol. You might be able to turn it though, it’s also a 15.25 dia prop so you can run it very high without loosing bite.
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08-29-2019, 06:27 PM #13
Hi there. I have a 186 Pulse with a 220 laser on the transom. It has an old Turbo 23" on it and spins 6000 @ 70mph, with no porpoise what so ever anywhere regardless of trim. Propshaft is just below the pad, running stock gearcase.
1984 19' Eliminator Daytona
245 JSRE Merc
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Grant Conklin thanked for this post
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11-08-2019, 03:23 PM #14
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11-13-2019, 06:07 PM #15
No setback, yet, but I do have a jackplate I plan to incorporate some day when I can get around to it. It is currently on the transom, all the way down.
1984 19' Eliminator Daytona
245 JSRE Merc
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