the deep

Good point. I threw a nose cone on my old OMC lower because it had the leading edge of a 2x4. lol I bet Art will not stay satisfied @65 for long. First boat that goes out around him will trigger the disease. $$$$$$$$$$$$$$$$$$

the deep

Pics of pics that didn't turn out too good but you get it I'm sure. Hotrodded family boat.

madbouyz

Speaking of the outdrive .. I've got a DPS/a as well but it's on a stock 5.7G something , and I've got a B3 on another boat .
The hydrodynamics of the DPS/a unit make the regular B1 look like a 22 cubic foot upright Amana refrigerator . So you know it's better in that aspect than a B3 and the Volvo F series props look like racing props compared to the Merc B3 version so I don't think there's anything to worry about in the old argument about B3 speeds vers B1 and subsequently Volvo DP .
A member who shall remain nameless and is no longer here was a Volvo guy as well as Merc and he said that the internals of the Volvo unit were vastly superior to the Merc stuff the main difference in build was that the gearcase casting was thinner .

A couple of months back a guy was on here building a monster motor for his boat , that if memory serves me was very similar to yours , I can't remember his HP number but it was over 600hp and I asked him to keep us up to date with how things went and ran in the end.
I was thinking in terms of the driveshaft safety coupler failing with that much power.

mcollinstn

HONESTLY the physics are the limiting factor, and the physics cannot be reasoned with or negotiated with. Period.

IF your hull was "40 hp shy" of lifting up onto one more strake or chine, then it would be worth pursuing that increase. Increments like that deliver results because you have several points in the hull's operational range where pushing just a little harder will get you up over another hump. We're all familiar with the spot where you're transitioning from "pushing water" to "planing" on top if it. That's a huge hurdle that delivers in spades. If you ever lose an engine in a twin while running 35mph you might be able to maintain that 35mph (or more) on the remaining engine. But if you stop to figure out what broke, and you're 20 miles from the nearest launch ramp you will be very sad to discover that your single engine will not be enough to plane the boat and you'll have to heas towards the ramp at 6mph.

Well, your hull has several lifting strakes thar represent smaller increments of reducing the wetted surface and friction as speeds increase.

Once your hull is running on the last set of strakes that will support it at speed, the only thing that reduces hull friction at that point is riding higher which lessens the effective frictional length of the wetted surface. These inscreases come with a parabolic relationship beyween added power and additional speed.

You can WANT more, but just because you feel your desired outcome is totally reasonable, the physics dont give a damn about what you think.

So HERE is a suggestion for you.
Remove everything from the boat that can be lifted out or uncoated. All the seat bases, hatches, doors, accessories, potty, tools, spare clothes, dock lines, anchors, etc. If you have a freshwater system, drain it. Bimini top? Take it off the boat. Two batteries? Leave one in the garage. Run the fuel level down below 1/4 tank.
Take the windshields off. You should have a pile of stuff weighing about 400 pounds or more.

Go run the boat on a clear day with very light chop. Run upwind and turn around. Run wide open WITH the wind wide open and toy with trim to find best GPS mph. Record the speed, the rpm, and the trim angle. As long as your engine rpm was not above 4900rpm, this test just showed you what your boat will do with 100 more hp with those things installed.

If you end up revving over 4,900 then you will need to increase prop pitch to see legitimate results.

This is the best, most accurate, FREE and totally reversible merhod of determining if you really want to add power to your hull.

Cap'm Kurt

Sounds like a great idea Mcollinstn. We've all "unloaded" the boats somewhat, but not to that extent. Sounds like a good way to tell for sure before adding the power.

I would love to have the time, energy, and ability to turn the boat over and play with different hull surface stuff. I've heard sanding at 45 deg angle, sharpening the strakes to a very sharp edge, even putting a tiny wedge across the back edge of the hull where the transom is(say 3/6" or so ) to help lift the boat, etc, etc,

One thing i experienced many years ago.... We had a "performance" knee board that had had half moon indentions all over the bottom every 3 to 4 inches. Like if you took a tennis ball and cut off 1/5 of it. Say 3/8" deep x about 1 1/2" diameter. That board glided FOREVER. We stopped using it because it was so slippery you couldn't hardly turn it. So it would be interesting to know if this would work on a v hull. Just on the back running surface when running fairly hard, say the back 5 or 6 ft just between the strakes.

Anybody have actual experience sanding or trying anything on the hull??

compedgemarine

if you want to look at the exhaust or see if there is any thing else in the pile of parts you may need feel free to give me a call on my cell during the day (no cell service at home) 954-270-2628 (still have a fla cell). parts are at the shop I work at in Clermont between Gainesville and Cleveland on hwy 129.
thanks
steve

Knot 4 Me

I had the boat that the 256 replaced for 15 years. 2004 260 SSi with a 496 MAG/Bravo III. Best it saw GPS was 53 MPH. Nicknamed it the Fat Ba$tard as my 6K LB Poly Lift would sink if the boat was full of gas and I stepped onto the boat. Had to get an 8K lift for it eventually. Here are a couple pics to show what he's up against hull-wise that will limit gains from tossing a bunch of HP at it. The two boats share the same hull design. There is a whole bunch of rounded surface area with a lack of lifting strakes on these hulls.

techman

I've spoken my peace about modifying this boat, which is a good looking Chap, by the way.

I've had Volvo's and DP's in my previous two boats which were Cobalt's. I can attest that the DP's are tough! I was enjoying a WOT blast down the local river when I t-boned a submerged log at top speed. The boat made a slight jolt but kept on going. Back to the ramp quickly to see what happened. The Skeg was gone and the prop set was mangled to the point where I had no idea how it was producing thrust or wasn't shaking itself to death. Repaired the prop set, new skeg welded on, and some paint and it looked brand new. That drive never gave me an ounce of trouble. No leaks, smooth shifts, etc. The VP motors are pretty much pulled off of the GM assembly line painted orange and given a marine ECM more or less. So they aren't fussy and have some nice features like the sea pump and fresh water flushing. Easy access to just about all service points.

Good luck finding more speed. I like the idea of ditching as much weight as you can.

Dragracer_Art

Your reply triggered a distant memory from a time when I had a Corvette. This was about 10 years ago... bone stock 2005 Corvette with the 400hp LS2 in it. It had a tune and mild mods done to it and made 396rwhp.

I had a guy roll up behind me one time in a 4dr Honda Accord. As we approached a traffic light (just the two of us) he ducked over into the lane next to me and lined-up at the red light. I thought this was suspect and immediately figured "game-on" this dude wants a piece of my Vette...
Light turns green and this SOB in the Accord took off like a bullet. I reeled him in and drove past him... but not without sweating it a bit. The little Honda must have been a turbo car because I barely caught and passed him.

Anyway... that night the search for a supercharger began.
I ended up with an A&A supercharger @ 12psi, Alkycontrol Meth injection kit, Fast LS2 intake, Stainless Works 1-7/8" headers, cat deletes, 3" dual exhaust and Flowmaster mufflers.

On the chassis dyno at Race Proven Motorsports it made 636rwhp.

All because I almost lost to a Honda.

True story.

Dragracer_Art

Yes... that looks like the same hull underneath...