Hi!

I trust you are well.

As you know I have a 1985 model Phantom 25 offshore performance boat. It is currently rigged with a Promax 300 SVS. The boat runs 76-77 mph spinning a stock A45 Tempest 25 at 6.300 rpms. I use a CMC powerlift and 7,5 inches setback. Propheight is approx. 2 inches below at WOT.

The Phantom 25 model was normally produced as a race hull for the European offshore circuit. The manufacturer and designer – Steve Baker – retired some few years back. When raced the boat was rigged with twin Mercury XR2 and Mercury 2.4/2.5 performance engines. See enclosed pictures of Agfa Blubird from 1985.

Steve Baker rarely check his emails, but I have been told from him that my particular boat is built extra strong .. and heavy. The hull weights approx 2.500 pounds / 1.150 kilos incl. the Promax 300 SVS and driver. The boat is narrow – approx. 5,5 feet wide. But is extremely stable at speed. No chine walk at all.

I have bought two Merc 2.5 EFI on my Phantom 25. It has been a long journey to get the engines. The hull is still very strong, and both my dealer and I are confident that it will handle the power.

Centerline to centerline:

The engines can be delivered both with the newer alien cowlings or the old style narrow square race cowlings. If I am correct, the closest you can get the engines with alien cowlings is 23 inches centerline to centerline. Do you know how close you can get engines using old style cowlings? 19 or 20 inches? What is the disantvantage and advantages mounting the engines as close as possible. What do you reccommend?

I will use Latham hydraulic steering with a tie bar.

Mounting height:

The engines will be mounted directly on to the transom not using powerlifts / brackets due to the balance of the setup. This requires a correct mounting height of the engines to be able to get best performance (read best speed). I know it will be a question between high speed performance - and cruise speed. Too high mounting height – the slip will affect the cruising speed.

Mercury Hi Performance reccommended engine mounting height is 8 (28 inches) inches if running a Sportmaster lower unit and in excess of 90 mph. This means a propheight approx. even with the bottom. It seems a little high for me. What do you think will be the best motorheight / propheight with this setup?

Rotation:

I plan to rotate the propellers inward to create bowlift. What do you think?

Propeller choice:

What kind of propeller do you reccommend for this set up? Should I try out Bravo 1 props or 3 blade chopper II props? Or other ideas?



Kind regards,



Toffen Gunnufsen

Lillesand

Norway

Toffen Now you have the correct motors for your hull. Mounting the motors as close together as possible will allow the motors to be lower on the boat with the right prop height and better roll center. I don't think bow lift will be needed with your set up.I would turn them OUT if it were me. I would say propshafts even with the bottom would be close to start. Cleavers or maybe choppers will be the fastest but bravo1 4 blades will give best cruise speed and best all around performance. I know you have worked hard on this boat and I wish you the best of luck and I know you will keep us posted

Hi!

Any more ideas out there?

Cheeers!

Toffen G

you will run cleaver props 30-32 inch pitch if you are running motors that high i had a 25ft phantom with a pair xr2s which was an ex raceboat also do you no where i can buy a 23-25or 28 hull i need a boat without motors just hull only undefined

Hi!

Thanks for answers.

Do you remember how high you ran the propshafts? I have been reccommended by some to mount them 1-2 inches below the bottom, and by others to mount them even - 1 inch above the bottom. If I am to mount the proshafts even with the bottom, I have to buy 15 inch midsections..

The engines will be mounted 19 inches senterline senterline using old style race cowlings.

The Agfa Bluebird was rigged for endurance race around UK (!) with twin Merc 2.4 engines (240-250 hp each), two gas tanks, bow trim tank, etc. The boat ran 90 mph spinning 28 inch Chopper props. What kind of speed did you obtain with your boat? And what kind of horsepower?

Check out www.boatmad.com regarding Phantom 28.

Cheeeers!

Toffen G

Hi!

I have received the engines and midsections now. I will receive the Sportmaster lower units next week. The engines will be mounted 19 inches senterline to senterline direct on to the transom. Propshaft height will be approx. 1.75 below for a starter. I will play with engine height. I will use 15 inch midsections with 2 inch built in setback.

I can get hold of the following props second hand (not for testing): 2 Mirage 27 labbed props, 2 Bravo One 28 labbed props, 2 Merc Offshore Cleavers and 2 Chopper II 28 props.

What kind of prop should I start with to achive good top end and good cruise speed. Gas prices in Norway is now almost 7,5 dollars per gallon....

Cheeeeers, Toffen G