# pocket drives



## firecat1981 (Nov 27, 2007)

> are these boats just equipped with every doo-dad to get them running shallow like the pocket drive and cupped props. i know they are tearing up the grass and obviously dont care about their lower units but damn how do they do it???


In short, yes! Post a picture of your boat sitting in the water. You may need to balance your boat better, adjust the motor height, add a hydrofoil or trim tabs, or your prop might be wrong for your boat.
These bigger fancy boats you speak of usually have hydraulic jackplates so once they are up on plane they can raise the motor. This works really well when you have a higher HP motor, but loading down a small boat with tons of gadgets is almost anti-productive to me.


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## luckovertme (Mar 31, 2010)

i dont have pics yet of boat loaded and wet. looking at it in the water loaded with out persons it sits pretty level, add me at 220# and girlfriend at 130 on the bow i believe its level. i do have a doel fin. i was also running this cut with a friend and he has a J-16 with a 25hp also. he did make it further than me before hitting bottom but i can float a lot shallower even with more gear and extra person. 

i am planning on rebuilding my johnsen this winter and thinking of glassing in a pocket tunnel but would hate to do it and find out im better off with out it. so from what i have been reading from this site is that i need the jackplate, cupped stainless prop and maybe some trim tabs. the questions i have is that without a pocket tunnel how much can i really raise the motor? on my ole highsider i was able to raise the motor cavation plate about an 1.5" without blowout from the bottom of the hull. 
right now on my johnsen the cavation plate is level with the bottom of the hull. should i try tabs first, then jack plate, then pocket tunnel? i am not trying to tear up the grass beds like those guys did but it would be nice to be able to run shallower.


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## firecat1981 (Nov 27, 2007)

typically you don't run both a dolfin and trim tabs, just one or the other.

Do not, I repeat, do not put in a tunnel/ pocket drive!!

I did one in my last boat and regreted it. You are right, you will need a cupped prop and a hydraulic jackplate to get any real advantage out of it. And beyong that you will really need more power to get any real advantage. The biggest downside is you will draft more at rest because of the less contact with the water surface. 

All boats are a compramise. Our small skiffs can go alot of places those bigger fancy boats can't. Sure they can run skinny at high speed, but if they slow down even for a second then they will have to wait for high tide before they can head home ;D


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## luckovertme (Mar 31, 2010)

thats kinda what i was thinking. i remember reading a post and i guess it was yours about regretting the tunnel. do you have a link for that post i couldnt find it today doing search? i guess i just have to be happy knowing im saving the grass beds and i can pole to the fish.


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## firecat1981 (Nov 27, 2007)

I'm not sure which post it was, here is my old boat build.
http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1247960551/0

and here is the new one I'm designing.
http://www.microskiff.com/cgi-bin/yabb2/YaBB.pl?num=1279666025

If I was running a 40-50hp with a jack plate then it would have worked out, but it wouldn't have floated in less then 6 inches of water.


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## Brett (Jul 16, 2008)

Only one way to make proper use of a pocket tunnel,
install a nosecone, low water pickup, powered jackplate,
surface piercing prop, and a big enough horsepower outboard
to push all the extra weight. But, with the new regulations
regarding seagrass beds, going that fast in shallow water
is going to get really expensive if you get caught!


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## luckovertme (Mar 31, 2010)

thanks firecat and brett, you guys have all the answers i was looking for!!!!


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## Brett (Jul 16, 2008)

If you absolutely feel the need to run skinny,
try one of these on a pocket tunnel...


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## B.Lee (Apr 29, 2008)

I know you guys wouldn't do the tunnel again, but in the short time I've been running mine, I like it. It's a compromise for sure, but it seems to be working pretty good. 

Perhaps the discussion should be more around the shap and size of the tunnel? Yours are both square boxes, but different dimensions. Mine is shaped differently, the intention was to clean up and concentrate the water more toward the top of the tunnel. Seems good so far.

I know I need much more testing and use to get a real solid opinion, and I'll give my honest input as this develops. I may just end up on the anti-tunnel side of the fence too!


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## luckovertme (Mar 31, 2010)

i know brett you are thinking the tunnel isnt worth it...but IMHO it seems like it did work for you if you are able to get a lil shallower. like what B.Lee said i think if you and firecat were to play with the shape more you might get better results. so do all that testing for me  ;D i think it all really has to come down to the type of fishing. i run fast through a lot of shallow creeks to get to my fishing areas...so running shallow is what i need. you guys ever think about building one of your models and putting a RC outboard on it and maybe run it the pool to test ride?then you could figure out where to put gas tank to get it level and all that jazz. thats what im thinking of doing.


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## Brett (Jul 16, 2008)

Never said it wasn't fun to build. Never said I didn't have a blast testing it.
Never said I didn't learn more hands on, than from all the reading I did.
What I am saying is that in areas with seagrass shallows,
manatee zones, pole-troll zones and no wake areas,
that a pocket tunnel really doesn't give you but 3 to 4 inches running advantage
over a simple flat bottomed hull. Unless you invest in a power jack plate,
trim tabs, nosecone with low water pickup and a surface piercing prop.
Then you can take full advantage of a pocket tunnel and run with
only 2 or 3 inches of prop and skeg below the hull.
Now we're talking more horsepower, transom weight,
more fuel and greater expense and maintenance.
Which adds up to a boat that doesn't float as shallow,
which was the main intent of my build, getting shallow.
For a well designed tunnel, you need look no further than the Texas Scooters.
They have it already down to an art form. Those tunnels
are more like funnels, that squeeze what water there is up into a hump
that allows them to run in just a few inches of water, in an area
where most of it is mud bottom. No seagrass damage.


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