tunnel hull aquasport

[aquaterra]

Im curious?
Has anyone ever seen a tunnel hull aquasport before? Custom or not.
If you've seen one please dish some details.
Thanks

[RickK]

Aquasport made a Cat in several sizes.

[akbridge]

I have seen people cut tunnels into 222 flatbacks before.  I don't know how they performed or rode.  What are you looking to do?  You could build a tunnel/pocket and get some favorable results if done right.  In general, with a tunnel you will lose some speed and ride.  But if you are going shallow it can be a great help or get you stuck on a sand bar even shallower.  Here is a link to a good design and theory http://www.bateau.com/studyplans/XF20_s ... ?prod=XF20  Rick I hope you don't mind me linking another forum site!  These guys know how to design boats to work very well.  Good luck!

[GoneFission]

I've seen some tunnels installed in the rear of some flatbacks and Ospreys.  I think there may be a pic or two of one on the photo gallery, but it does not quite seem to be working...       It's not an easy mod, because the keel of the boat is a significant structural member, and interrupting the structure with a tunnel requires some good planning to ensure hull loads and transom loads are considered.  

I think if someone is hooked on the idea of a tunnel bottom, you would probably be better off buying a boat with the hull you want versus trying to put a tunnel in an Aquasport.  Just my $0.02.

[aquaterra]

Well
im am redoing my 19.6 from the ground up. my dog loves to swim so i wanted to make it nice for her to get in and out. the thought hit me to beavertail it and then put in a tunnel hull.

all this is theory to me now and wanted opinions...
planned on runnin solid stringers past the lenght of the transom..through the transom for the beaver tail. keep the boat sealed at the original transom but put a floor out back so the dog could climb up on her own. i know kinda dumb but the more i thought of it the better it sounded.. then i thought, since im doing so much modifying to it what if i just put a tunnel pocket in it sow when im runnig with a jackplate i could lift the lower unit to be protected by the hull. in case i hit a rock or something shallow..
 
not sure if im gonna do it but since im rebuilding it anyway nows the time to play if i can.


o... another thought is that the beaver tail could provide a little more floatation for a 115/150 and offset a lil bit of the engine weight.


more  advice/opinions         please

[akbridge]

Hmmm interesting.  It sounds like you are trying to make something that looks like a Texas style boat.  Something like this?
http://www.shoalwaterboats.com/19%27_st ... g_Boat.htm  If so I think you would be time and money ahead to buy such a rig.  There are tons of these style boats in TX and they are supposed to ride good and fairly dry for what they are.  

Or you are trying to make a swim platform at or below the water line.  Which could be interesting if you would be extend the length of the hull.  So that would take care of the engine sitting further back.    I have heard that a tunnel needs to be about a foot in length for every inch of height gained in the tunnel.  It sounds like an awesome project, lets see what ya got.

[GoneFission]

The only real reason for a tunnel hull is draft, but those Texas boats have a 9" draft, the same as a 196.  OK, so you can jack the motor up a bit and get into more shallow water - save your money and go to a jet drive outboard.  With no prop, the jet drive only needs 3" of water under the hull to go, not 15-16" like a prop.  IMHO, an Osprey or flatback with a jet drive outboard would be an awesome shallow water boat!

[John Jones]

The only real reason for a tunnel hull is draft,

The only real reason for a tunnel hull is running draft.  ;)  
They don't float as shallow at rest or low speeds.

I considered a tunnel mod to an old bass boat I rebuilt several years ago.  The more I thought about it, the less I was interested.  This side of Florida has so many idle, slow, or off plane zones and speed limits that being able to buzz shallow is almost moot.  Manatee County is slow speed only within 300 feet of any shoreline including islands.  Not only that but I have no use for people that buzz the flats so why would I spend time and money to have a boat that would do it?  There will be more slow zones and I think in the near future there will be fines for trenching the flats.  Already they will burn your azz for it in the Keys.  I had rather be able to fish shallow.  I'll get in and out of shallow water with my pole or trolling motor.

[RickK]

I watched a few of the Shoalwater videos and they repeated said that their boats can pound through any wake - I bet.

[John Jones]

LOL
Not the best choice of words.

[aquaterra]

well i took measurements and checked out bateau.com and if i decide to do it im thinking of
3feet in length and about 20 inches wide. That shoalwater boat in texas is kinda what im looking for except i want to run to the reef on choppy days if needed and that i just dont trust a flats boat to do. or else i would get one of those.

im still not sure ill do it but it seemed like a cool concept at the time.

i guess i could essentially get the same concept out of a jack plate without the tunnel, just not as extreme result???

plus at 3ft long 20" wide would i actually loose much floating draft? that doesnt seem to be to big of a section and theoretically it would still be displacing water to help the boat float.

just what im cooking up inthe old noggan.

bobby

[slvrlng]

71 flatback built a tunnel into his rebuild. Here is a link to his thread. Maybe he will see this and post a comment. If he doesn't try a PM to him.

http://classicaquasport.com/smf/index.php?topic=2599.0

[akbridge]

Shoalwater does make some neat boats.  But they are flats boats.  I have heard of folks taking similar boats out 20+ miles.  But that's not for me.  I would take one a few miles offshore to a reef.  But that is a personal call.  

I can run as skinny as I desire with my 170 and a jackplate.  But again that is a personal call.  

You will gain draft with a tunnel.  It might not seem like much, but every inch matters to keep the deck above the water line.  A tunnel does not displace water at rest.  It fills with water.  The bigger problem with tunnels is that they generally slow a boat down.  If you look at the speeds Shoalwater is getting and compare it to a AS they are generally slower.