The following is from Tegque on tech, Power boat mag.

I have a 1999 21' Baja Hammer. It is equipped with a 7.4-liter MerCruiser engine, and has a top speed in the 65 to 70 mph range. It is great for the lake we live on, but occasionally my son and I take it to a much larger lake for a poker run.
While the top speed is OK to run with most of the boats, the handling gets a little out of shape especially when one of the much larger boats goes past and we cross its wake. My question is would trim tabs help or do I just buy a bigger boat?
Alan Gonzalez
San Antonio, Texas
Answer: Adding trim tabs would help to settle the boat down in the cross wakes. Using them will result in a reduction of your top speed, though. When they are up, the boat will be the same as it is now. They can be lowered just enough to improve control without scrubbing off too much speed. I would install them toward the keel, a little in from the traditional mounting location out by the chine. This will allow them to still be effective when the boat is riding high up on the keel and the chines are pretty much out of the water. I also would consider mounting the tabs horizontally as opposed to parallel to the bottom surface. This will allow the outside tips to touch water before the whole plane does. Sometimes, when the planes are mounted parallel to the bottom, the angle of the plate accentuates the chine-walking motion as the boat launches off each plane alternately.

Thanks for passing along that post NightHawk. Very helpfull.

ok i know this is reeaallly old but hopefully this'll bump it and someone can chime in

i have a 21 ft baja 208 islander and recently recieved lever co 12X16 tabs and mounting them is becomeing an issue i have done a bunch of reading and research and no one seems to have a solid yes this works to correct this answer

my problems are porpoising and chine walk at about 55 and faster and its really making passengers uncomfortable IE girlfriend and i was informed it needs calmed down before i add the 177 blower ha ha and i am really ready for the blower got a new X drive and everything guys little help please

They will provide a little more running surface but but not much. You need to mount them flat not at an angle. Also make sure the are at your running surface. The thing is this does not cure your problem. Dropping tabs to stop a porpoise is just a band aid and just causes drag. The porpoise is in yourhull design. The quickest and easiest way to tame it is to get a 4 blade prop. The rev4 does wonders on a bottom like yours. Should take the porpoise away and give you way better control.
Also if you are chine walking at 55 you might want to re consider higher speeds it doesn't just go away it gets worse.
What kind of steering do you have? If you say stock cable steering this is going to turn into an ugly boating experience with the gf. They don't like getting tossed out of a boat you are driving(;

i am currently running a 4 blade stiletto and its seemed to make the chine walk worse it did however seem to help the porpus stock cable steering is a yes and been looking at the outdrive dampener set i've seen on a guys hammer on the water. and you said flat? kinda one of those subjective things flat with the hull bottom or flat as in flat to waters surface

Safety issue with mounting paralle(to water) is as follows. Imagine your v making a right turn. Boat leans to the right on it's axis. Transom of boat moves to the left of the center of gravity(ford to aft). Let's say you hit a wave as you are turning and your boat then loses it's inside axis and tilts outside axis(already a risk for outside roll), think about the inclination of your your parallel mounted left tab. It is now perpendicular to the water. This would drag badly as the transom is washing to the left greatly increasing likelyhood of rollover.

Here is a few thoughts. Don't fix the porpoising on that hull with tabs, find out why it's there, it shouldn't be. How is the condition of the bottom? If your bottom is good, the place to start is props. If you want to try a 4 blade, you should look into something not too big in dia. like the Vensura. Prop torque from larger diameter props can create chine walk problems as it sometimes manhandles a small hull like the 208. If your drive is deep, look into the LaserII and Mirage+ as well. These three props have a lot of bow lift for their size and I will say that the Vensura is a personal favorite of mine for your type and size of hull. The Rev4 is indeed a great prop for the Bajas, but your have a 20' boat, so start trying props for the size of boat, ie. Vensura or LaserII. If you feel those two are not biting enough, the M+ and Rev4 are next in line.

yes my boat is a little guy and i actually just spoke with brian from instatrim GREAT guy very helpful. he said on that hull they used to supply baja with 12x11 single ram tabs and was pretty familiar with my hull. he said i made an exelent choice with the longer dual ram tabs from his company and that they should be mounted about 3/4 of inch from bottom of hull on the angle of the V. and with cylinders all the way up should have about an additional 1/4-1/2 inch above the bottom of the hinge. he seemed overly confidant that the tabs will correct my complaint.

and as far as props go i have tried a variety of props none of them seemed to affect the porpous till this stiletto its a 14 in with a 20 pitch i can run a tiny bit of trim with it b4 it starts hopping and man its got bite out of the hole and it gps ed as fast as my 21 pitch labbed stiletto advantage 3 prop i am happy with just not the ill handeling and speaking with an idividual in my area who used to sell baja's in the mid 90's said that boat with that engine just naturally does that its to engine heavy

appreciate the imput and concern guys also i am starting to hesitate on adding more power with the steering concerns poker run hinted at whats the general opinion? i am only looking for 70 and to get there fast even if i have to under prop for that speed as long as it leaves good

Ok, I have a baja too.... You could have hook in your hull causing the issue. also you could have aprop that does not exibit enough bow lift at 55mph. i have a labbed 24 4blade bravo that will porpose. but i have a labbed 233 mirage plus that will carry the bow all day long.

fixxer22