OK, I have a 28’ Checkmate with twin 502s with Stellings Boxes and Hydraulic Steering and am looking at putting side mount Whipples on the engines. The boat has an empty cabin (just facing couches and the V Berth cushions) so it is light in the bow. This combination is very stern heavy and with the addition of the Whipples, it will be worse. The question is, is there an ideal center of gravity for a standard deep V hull? Is it possible to have the bow too light and the stern too heavy for maximum speed and good handling? If yes is there a formula for proper hull balance? I know that some cats are set up with the engines forward to balance the air entrapment hull but do not know if this is important for a deep V hull with no steps or a pad.
Thanks.

If you are going to want to go faster, then moving the CG aft is actually a good thing, and will help carry the bow. It is going to take more tab to get it on plane, and the tradeoff is that you won't be able to stay on plane as slow as before. Fuel consumption running at cruising speeds will go up due to having to use more tab to keep from porpoising, but that is the trade-off on a non-step hull.

Now, twin 502's & boxes is quite a load for a 28. If the setup was good before, though, you should have a good starting point once the blowers are added. You can always bolt some ballast into the nose if it needs it.

A thing to consider. If you installed alu heads and performance exhaust manifolds or headers, you would lose quite a bit of weight right there. Heads could net you about 70lbs pr. engine, but I'm not sure on the weight savings on something like EMI or KE manifolds and Hardin, Stainless ect. headers. If going SC, alu heads and a good exhaust would not be a bad idea anyway.

I went thru this a few years ago on my 272 Baja, except I had the opposite problem, too light in the rear and it wanted to bow steer/not air out unless I had 4 passengers (300-400 lbs in the back seat), I bolted some removable ballast in the very rear of my molded swim platform, to the tune of about 50 lbs. It was just a starting point and turned out to be too much (which will be similar to your possible problem). When I would plane out the nose was then in the sky and boat acted REAL stern heavy as if I had 500 lbs in the back seat. I cut the weight down to about 20 lbs and it works about the best its going to. When I was reasearching the boat balancing answer I talked to several people, I was basically told you could sling your boat on a single sling and see where the balancing point is but really that is not necessary, when you get your boat done try adding a little weight in very tip of the bow if it acts stern heavy. Remember , leverage is on your side too, thats why 50 lbs in my very stern acted like 400 lbs in my back seat (approx 8 feet FURTHER BACK) so it won't neccesarily take all that much weight, Smitty

you can make an easy 550hp from those 502 mpi engines. valve job and some mild head work with those heads. new cam and rockers. VERY reliable setup.

your going to need some new drives and or drive work with bolting on SCs.

there is no magic CG number for your boat.

good luck on your winter project!

someone has to say it

get rid of the fat chicks.

I think you may be on to something. I could toss a donut into the cabin and see if I like the way the boat handles with more weight in front?

Actually, I have been considering ways to change the balance of the boat for awhile. The simplest would be to move the batteries forward in the boat but I am not sure they could survive the additional travel / pounding. Other ideas are aluminum heads, aluminum flywheel, moving the engines forward (can be done fairly easy due to the extension box drive shafts but not cannot move very far due to the fuel tank in the floor). I am just trying to decide if any of this is worth the effort. It seems like I read a while ago that a 35' Fountain was faster than a 29' model with the same power because of the hull balance? Don't recall if that was with stepped hulls or the previous models.

Sounds like a sweet boat you have! Don't forget to upgrade your drives. SCX upper and lower/ SCX upper sc lower/ b-max/ etc will work great.

BTW I love my prochargers.

buy some 25 lbs lead shot bags at cabela's, gander mountain, bass pro shops or outdoor world...u get the idea. the bags will stay put where ya place them up front. the bags can be moved around the boat to make drastic changes without going back to the docks. i would buy a 150 to start with.

removing weight from the back will have very little effect. adding weigh to the front will have far greater effects. adding weight further away from the CG with also increase your moment of inertia too.

Since the boat will naturally carry the bow, use stern lifting props like Hydro QIV's