rocker tabs fixed drive
 

would rocker tabs be a good idea with a fixed surface drive to give bow lift

Tabs, rocker or otherwise, don't give bow lift, they reduce it. on surface drives I've seen a 'tab' mounted to the drive that gives bow lift... you could use tabs to counteract that.

Look at the Arneson tabs. They are designed for exactly your application. High-rake props will bring the bow up too.

http://www.offshoreonly.com/forums/s...d.php?t=177694

I haven't seen them actually create any bow lift unless the hull was originally designed to use them. I made the assumption (which is bad because I have no idea) that the original hull wasn't made to use them. The big cat hull in the thread above is a perfect example of a hull designed to use rocker plates.

what rake is normal i just bought a 17x26 mercury how do i measure the rake

You need to move this to the "prop" section and have one of the pro's that visit the board work with you on this. Unlike outdrive props, fitting a surface drive prop can be tricky. It's tough to get a borrowed or loaner set.

tell me about it surface drives are almost unherd of in ireland and no one makes props either

Rocker plates can add add bow lift by doing what they were designed to do, adding rocker to the hull.

anyone an idea what tabs would cost for a 26ft

Call Arneson. My guess is alot more than a good set of properly-matched props that will give you some bow lift.

How about some exact description of your boat, drives & power. That would help everyone in making recommendations to you. There are alot of issues that come to mind that would have to be eliminated. For example- if you had the boat on the wrong trailer and it has a big hook in the bottom, neither tabs nor plates nor anything short of divine intervention is going to help your problem.

gerard,

what type of hull do you have? I spent a lot of time and money trying to make bow lift on my surface drive powered boat. I would say that rocker tabs will not work (acknowledging that I don't know your setup). I also found that bow-lifting props were not enough.

its a 26ft fletcher zingaro with a 440hp diesel yanmar and 2speed transmission the drive is fixed at 6 deg and the all in weight is 2.3ton i was running a 29 4 blade rolla at 60mph but it was way too big 700rpm less than its max 3400rpm the hull is simlar to a sealine or bayliner . i have just bought a second hand prop off rr performance hopefully get to try it in a week or so due to the poor weather here at the mo

any help will be much appreciated

cheers gerard

Call Rick at Arneson.

Since surface drives need rocker in the hull and rocker plates add rocker I would think they would work. I've talked to Rick and he's a great guy and will take the time to talk to you.

BTW... Geoo (with the famed 120mph Donzi) picked up bow lift and over 10mph by installing rocker plates on his X18.

funny i was talking to rick today about a spline adaptor and have to call him back tomorrow i must mention it to him an see what he says

How about moving some weight toward the stern?

i have already gutted the boat out and rearranged it. all the weight is as far back as i can get it even the cuddy is empty

I added a horizontal fin to my Donzi.

It seemed to do the trick. Arneson rocker plates should help as well.



Jeff

how effective was the horizontal plate did you pic up any more speed or did it cause drag and reduce speed

cheers gerard

It lifted the bow quite a bit in turn increasing speed.

Jeff

thanks for the reply mate

what was your set up and how big was your plate

cheers gerard

The part I used was a bronze casting.

It's about 6 inches wide at the rear and 2 inches at the front.

You can make your own by bending up some aluminum plate.
You will have to mess around with the installed angle a bit.
Run as little angle as possible to get the job done otherwise you will be adding unnecessary drag.


As far as setup, what are you looking for?

Jeff

was wondering your length weight and power and roughly what angle your drive is at wot

the first two thirds of my boat is completely gutted out to try and reduce weight upfront and its still diping the bow i cant understand it.

i see you have choppers on how do you rate them compared to cleavers.

cheers gerard

My boat is 20 ft. long It has a 5.7 liter Chevrolet making 360 hp at the flywheel. running weight is 3100 lbs. with 20 gallons of fuel.

As far as the drive angle I haven't measured it. I have adjustable trim. Wouldn't be able to measure it until spring time.

The round ear chopper will give more bow lift than the cleaver.

Are you using a cleaver? The cleaver would work great for getting the maximum speed. The round ear or chopper would be better for all around use, it will also give more bow lift.

Post some pics of your setup if you can.

Jeff

take a look at my thread PROP PROBLEM and let me know what you thiink ill try and getyou some pics tonight

cheers gerard

Gerard this is one way to get the bow up!

By the way I lit the engine up see

http://www.youtube.com/watch?v=fWT69AfONJk