Extension box
 

sound like a school kid with this question, but hey all all learn something new every day..

what is the advantage of a extension box?

I have a cat ..25 sxt warlock.. would that help at all ?
thanks .

By moving the propeller and gearcase further aft, several things happen:

1) The drive can be set higher (x-dimension) on the transom. You'll still be able to immerse the prop at low speeds, but as the boat flattens out, and the wake rises less at higher speeds, the water level on the drive will lower, effectively raising the drive, and lowering drag.

2) The drive gets more lever arm over the boat, allowing more bow lift (or stern lift) depending on the prop and trim.

3) The props get to stay in the water a little longer in rough water. When the prop is in and the boat is out, you go really fast.

4) Some manufacturers sneak their transmissions into them, or integrate the steering, which saves room in the engine compartment.

5) They look really cool. After you see your boat with them on, bolting the drives straight to the transom looks cheesy.

Note that in most cases, at least with Speedmasters like I have, converting to extension boxes requires you switch to driveline transmissions instead of plug-ins, and possibly an engine position change. Steering will require tower bases, at a minimum.

With your warlock cat, assuming its a single, moving the drive aft won't do much, as its already in clean water anyway. You can make drive height adjustments by getting shorty lowers or spacers, and be way ahead. You have to be really careful with a small cat, as even minor weight movements could shake up the handling.

it will not help your boat but it will look cool...

I resently drove a 2002 sxt and it hops on smooth water.502 500 merc carb mtr. stk.It has an Imco shorty and a set back box ,apx. 10 in.I like it and may buy it but I hate the hop.My Talon's never hopped.Will a std bravo help,getting the drive and prop deeper in the water ? Any suggestions ? hf...

It can help hop and porpoising issues. Sometimes when you move the lever point back and the prop up, it can create hop and/or porpoising, especially at lower speeds. In some cases, choosing another prop can help as well.

Stellings boxes
 

These will help everything
Help your drive explode
Help Merc sell parts
Help you spend more $$
Do not use stellings, The design eliminates drive coupler! This coupler cushions shock loads to the drive.

whats speeds were you getting with the shorty and box ? thanks

There is an up side to Stellings boxes, you don't need to raise or relocate the engines because they use a drive shaft to conect up to the engine. You can retain the coupler by using drive line bellhousings and transmission adapters. I chose the Stellings for this reason. I also moved my engines 2 ft forward and the Imco straight shafts would not work. I think I have the best of both worlds with my setup.

By the way, retaining the coupler is NO guarantee you won't pop the drive anyway.

would one of these boxes work on a donzi 22 classic want to convert from trs to bravo want to get rid of trans also will i have to move motor back or can it stay where it at

The boxes are all Bravo bolt pattern so you'd still need to glass in the transom and make new cut outs. I believe there used to be TRS boxes available but I haven't seen or heard of any for years. There might have even been conversion boxes for what your trying to do but again, very old parts and hard to locate. That being said, if you go stellings and set it up like I did with the couplers and shafts ther engines could remain in place, you would need to fab up some rear mounts. I used off shore plates front and rear on rails.