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BaitTank

LT 20 & Jack Plate

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I cant find the old posts, 

I know this is an old question.  I may have access to a used CMC Hydrolic Jack plate at 5 inch set back.

I thought I read a while back, no more than 4-5 " on the setback for an LT 20?

only hanging a 150 yamee on it

thoughts?

thanks

matt

 

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I have a LT20 with a 4" setback bobs jackplate with a 225 Mercury but haven't had a chance to run the setup yet. Hopefully within the next month or so I will be able report back with more information. If you run shallow I don't see how it can't help. 

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Had a 1998 lt 20 with 200 yamaha on a bobs 6 inch. Sat a little low in rear but nothing that bothered me from what i remember. Only issue was added stress on transom. I would lose water pressure depending on speed if the jackplate was all the way up

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were you able to keep the bow up at WOT?  I get spray at WOT in front of or in line with the center console.  At lower speeds I can keep the bow up and the spray is behind me.

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Probably a little underpowered with the 150 but it'll work. The LT20 is not a light boat and has a big footprint in the water. Get a good 4 blade prop for sure ( 14 x 18 ? ). You can throw some Boyesen reeds and a Hydrotec tuner on that motor and it'll act more like a 200 :). A 4 blade prop will hold the bow up better too if that's what you're after.

-Mike

 

 

HewesHPDI-Boatview-4web.jpg

NewYamahaHPDI_zpsc9xysx5g.jpg

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thanks for making me drool all over the image you posted with the 200vmax......LOL.....

Is that a CMC jack plate?  what is the set back?   The Jack plate I was going to buy off craigslist was sold out from under me....argh.......

are you able to keep the nose up even at higher to WOT speeds?  When I get on plane, I trim up until I feel the hull go loose.......If I then put the throttle down , the bow slams back down to the surface.  I am trying to get the setup so the bow will remain up at higher speeds......thoughts other than a 200hp motor dynoed to 300hp....LOL

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Not trying to start something, but 4 blades generally lower the bow and 3 blades raise the bow. You could try a tempest. The bow goes further down at higher speeds because of the bottom of the hull. It begins to push down. I could never get mine to raise, but then again i do a bunch of prop testing as i only owned it 6 months

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16 hours ago, BaitTank said:

thanks for making me drool all over the image you posted with the 200vmax......LOL.....

Is that a CMC jack plate?  what is the set back?   The Jack plate I was going to buy off craigslist was sold out from under me....argh.......

are you able to keep the nose up even at higher to WOT speeds?  When I get on plane, I trim up until I feel the hull go loose.......If I then put the throttle down , the bow slams back down to the surface.  I am trying to get the setup so the bow will remain up at higher speeds......thoughts other than a 200hp motor dynoed to 300hp....LOL

It's the stock Bob's Jackplate they came with, 6" setback. With the 4 blade Stiletto on it I can raise the bow fairly high at WOT, to the point where it gets squirrely and dances and you spill your drink ....and have to circle back to pick up all the crap that flew out of the boat.... The LT has a significant V-hull, unlike an ActionCraft or most of the other brands out there. With a 3-blade on there it starts porpoising much earlier if I try to trim the bow up very high, so I just let it fall to where it wants without the porpoising and hold on. In that photo above that's a Stiletto 4 blade 14x20 on the motor. If I run a 3 blade it's a Stiletto 14x21. Generally I run the boat with the 4 blade on it because it just performs better overall.

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there is a sweet spot with the LT........with the 150 so far, its 30-35 mph with light trim.....any more trim and we have a porpoise fest and yard sale like you mentioned.   She cruises wonderfully at that speed, but I want the nose up at full throttle and 42 mph if needed.   Right now the bow is flatt on the water at 42mph.  If I went to a four blade, I would have to go down from a 17 pitch I suspect.  4 blades will give me more grip, but will take a few MPH away... and RPMS.   I went with the 3 blade to get my rpms up.  5300rpms at WOT.  The guy who had it before me had a 21pitch on there and was lugging the motor at 4600RPM WOT.   I suspect a good 3 blade with more cup and rake may be the answer and coupled with a jack plate to change the balance of the hull.    The prop I have on there now is from Marcus (Funky Monkey).   I have an email in to him, but he has not responded.  

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Load all weight in rear as well. Something you can try is fill the rear livewell and see how the boat reacts. Not the same as a jackplate but will add weight in the rear to see how you like the boat sitting and/or driving.

I will say, as far as the boat riding bow heavy, i have yet to hear of someone curing that issue.

What i do find interesting is how you are porpoising, from what i remember mine didnt porpoise. A jackplate will usually make your porpoising worse as it shifts weight further towards the back. A 4 blade generally helps with porpoising because it raises the stern, but this in turn lowers the bow, a double edged sword. From what i remember, my lt20 with a 200 vmax was spinning a 19 or 21 3 blade stiletto with a 6 inch bobs jackplate. The prop had pretty bad grip high on the jackplate

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the porpoising is USER generated....its an effect of trimming too high on any boat.  I can get her porpoising any time I want, but it is user generated.  I did have the seacock closed, so the live well was empty.  I will try that this weekend.  The setup in my opinion needs more leverage at the stern.   When the motor was mounted all the way down, I had more leverage and was able to hold the bow up longer before it dropped at WOT.   A stern lifting prop will not help the situation.  Bow lifting is needed with cup and rake.   The prop I have has cup and rake and porting.   3 blade.  PTZ 3R17PCLYX200, port 5/16”

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