Tunnel tab
 

Will a tunnel tab stop the hop on a 25 Motion in the mid range?I would really like to find someone who has experience with a tab on a 25 with outboards.

Dayum Casey... 70 views and not one response? Figured someone might know something about tunnel tabs. Maybe you should post the question in the Skater section...?

Personally I would not put a tunnel tab on any cat. I think they are way too dangerous. Try adding weight to the nose of the boat (sand bags) and see if the hop goes away. If it does then just move the some of the heavy componets towards the front of the boat (battieres, ect).

I would try different props. Maybe you can find a prop that doesn't hop as much. I have heard that tunnel tabs are a little dangerous.

New to looking at the Cat section of the forums, but why are tunnel tabs so dangerous?

I have heard they are dangerous.It just gives me the red a@# when i can't get the boat to lay down and act rite.It doesn't do it all the time but when it does it's frustratng.My friend said to put weight in the nose.I dont mind moving weight but not adding.

Someone correct me if i'm wrong,When using a tab you push the bow down but what you also do is compress the air in the tunnel this causes the strern to lift .This will lift the props and the skegs out of the water.When this happens the boat may decide to try and prop walk and then you are along for the ride.My propshafts are an inch and a half above the bottom of the boat so that doesn't leave a whole lot of the rudder in t he water.I hope this means cents to ya KAAMA.

Yep. perfect cents. Thanks.

I have a 1990 Motion with new 300xs on it. I was considering a tunnel tab. I have tried turning the props out and now in. I like in better. I think the best thing for you to do is get some seat time and lots of it. You will change your driving style and you will be able to drive through it.
Are you running setback plates. My motors are bolted directly ot the transom. I am considering puting the setbacks back in, I can only get the prop centerline 1-3/8" above, so I have lots of water pressure.
Oh, I have re-located my stereo battery up front under the deck and do not charge it off the alternator. I installed a trickle charger to it and I plug it in at the end of the weekend.

I do have 6 inch jack plates on the boat .Adding the plates gave me 3 and a half miles an hour.I have not tried turrning in yet.THats my next step.Good to talk to another 25 owner.What will that thing run with those 300s?

Which motors do you have.
I am running 108 with 300xs, offshore mids, 1.62 sportmasters, bolted to the transom, I have 15x34 3 blade mecury cleavers. I am considering putting my jack plates back in. I have not tried them with these motors.
Good luck.

http://www.youtube.com/watch?v=DkGYxpvWgwk

This is good advise! :grinser010:

Nice video. It looks like it porposies a little in the midrange?

My boat has 225 Pro Max's.Offshore mids with sportys.With merc 30 by 14 1/2 cleavers it will run 97 -100

My boat has 225 Pro Max's.Offshore mids with sportys.With merc 30 by 14 1/2 cleavers it will run 97 -100 depending on fuel and motor height.I have a set af 28 cleavers that will run around 96 but i have to turn the motors 7800 to 8000.I really don't like zinging those motors up that much.The boat acts alot better with the 28s though.I have a set of 27 four blade hydromotives that i've been experimenting with.Here's the deal, if i jack the motors up with the 30s it will run the best mileanhour but it will only air out and stop hopping with a good chop are wind in the nose.I just think at times like these drop the tab down and when it airs out bring it back up.If i drop the motors down it will drive through the hop but you can either go 45 or 75 it will not run in the middle .I thought maybe the tab would allow me to run wherever i wanted .I know now why i see alot of cats with hydrolic plates.Thanks for all advice guys.What i really need is more horespower.A pair of 300x's would prolly do the trick.

Yep, 300x are great but hard to find.

There was a pair on S&F for a great price .I think they lasted a day.

Part of the problem you brought up yourself. The boat is a little underpowered with the 225's. In flat water every true cat will porpoise. My 39 does at 70 mph. I have owned three Motions and all three had a porpoise. I have owned or been in 21, 24, 28 and 32 Skaters. Same thing. The hop can be real annoying but you have to simply not run at those speeds. Cruise slower or go faster thru the hop. Raising the engines can make it worse along with being too low. Having more power can push the boat thru the hop very quickly. The video with the 300XS engines is a prime example. Couple of hops and you are thru it. I would not use a tunnel tab. Turning the porps in will help as that give more bow lift. Engine heights are critcal to making the boat run right as well. Prop selection can have effect as you are finding.

Very well said...

I think having a forward ballast or moving some weight forward with the 300XS will be the best of both worlds.

Sure, not everyone can spend $35K on new outboards... so I think having a balanced weight system would be my first avenue for a better riding hull.

I moved the stereo batteries up under the deck of my 25 motion. I also rigged up a trickle charger and plug it in at the end of the weekend. I run two Rockford Fosgate amps, 1- 15", 2 - MB Quart 6x9's and two MB Quart 6.5", I also have interior LED lighting. I don't drain the batteries, I don't run the stereo unless we are floating.

I am considering putting the jack plates back in and moving the engine only batteries up under the deck, but then I have to run welding wire up under the deck, that stuff is heavy.

I think lots of power and seat time, you will be able to drive through it most of the time. There are times when I have to back out of it and start again, but that is usually my fault. A head wind helps. If the water is smooth it will porpoise longer, chop helps.

I have run 107 into a 8-10 mph head wind and the boat is feels great.