MOTION 35 outboard rigging

[Garmin]

I'm rigging a 35 Motion cat with triple outboards on CMC jackplates, where should the outer outboards be rigged, how close to the tunnel? the engine height is 25" for the outer engines and 20" for the center engine? also some help as to engine height both for the outer engines and the center engine would be appreciated.

[AirRide]

What gearcases, exactly, are you using? Merc power, or? What does the boat weigh dry? What will the boat weigh with a full payload? Pleasure boat, or?

[Garmin]

300x with Sportmasters

[AirRide]

A conservative installed outer engine height, not knowing weights, etc,. would be to have the propshafts level with the bottom of the sponsons. A lot more boat details are needed. Install the outboard engines so that the absolute largest diameter props that you would ever use, probably 15 1/2" diameters, are completely out of the vertical tunnel surface slipstream. I would keep the prop blade tips at least 2" out from the tunnel. At slow & mid range speeds, there is a large volume of water that enters the prop slipstream off the tunnels vertical surfaces, that, if you have a choice, want to stay out of. Install the center engine 2" above the bottom of the sponsons. This is only a starting point for the center engines installed height. You will definately be moving it up(or down) from this point, depending on water pressure, slippage, propping, etc., through much testing. Every offshore cat is differant, with regards to design lift at speed & angle of attack, etc. Again, if the boat is unusually light in weight, or unsually heavy in weight, there are many, many more variables that come into play, concerning installed height, width, & setback.

[mikesufka]

Just curious where you found the 300X's? Or did you have them?

Thanks.

Mike

[fast fun 2]

We ran a Prostock 32 Skater in the 1990s...2.5s right on the transom was the best balance...I know there similar hulls

[Vicious]

We ran a Prostock 32 Skater in the 1990s...2.5s right on the transom was the best balance...I know there similar hulls

They are simular but the Skater is a lighter bagged boat compared to the hand laid squeeged method the extra set back on the HEAVIER 35' will help.
I would say Air Rides set up guide lines are right on the money my transom layout for my 31's are real close to that.:thumbsup:

[Garmin]

i had someone on Offshoreonly tell me somthing different, with the left and right mounted engines with the propellor tip running 1 to 1 1/2 inch in the tunnel, and the center engine 2 inch above the lowest point of the side sponsons. what do you think? thank you so much for all your help.

[mikesufka]

I would call Larry Goldman. I think he's the big Motion guru.

http://www.xtremepowerboats.com/index.php

Another guy to talk to is Brad Zastrow. He's had a ton of bigger "go-fast" cats and owned a 30 Motion with triples. He's on S & F.

Mike Sufka
St. Cloud, MN
Spectre 30 w/Twin 300 Mercs

[fast fun 2]

The are simular but the Skater is a lighter bagged boat compared to the hand laid squeeged method the extra set back on the HEAVIER 35' will help.
I would say Air Rides set up guide lines are right on the money my transom layout for my 31's are real close to that.:thumbsup:
Gotcha :cheers:

[Michael J Giesler]

check with brad Zastow he had one with tripple's can't remember if it was a 30 or 35 118mph boat:eek:

[mikesufka]

check with brad Zastow he had one with tripple's can't remember if it was a 30 or 35 118mph boat:eek:

Brad Z had a 30 motion with triple 280 mercs. I think it ran 114 MPH or something like that. I'm sure he'll check in here - he's probably snowmobiling this weekend.

Mike

[donmac]

when I was running a heavy tripple rigged cat, i had to run the centre prop with a 2'' reduction in pitch to get all three rpm matched, I didn't have hydraulic lifts and the hull was heavy ''Baja Bandit p177''

[LOWBLUE3201]

i had someone on Offshoreonly tell me somthing different, with the left and right mounted engines with the propellor tip running 1 to 1 1/2 inch in the tunnel, and the center engine 2 inch above the lowest point of the side sponsons. what do you think? thank you so much for all your help.


I have heard the same.

[Vicious]

when I was running a heavy tripple rigged cat, i had to run the centre prop with a 2'' reduction in pitch to get all three rpm matched, I didn't have hydraulic lifts and the hull was heavy ''Baja Bandit p177''

Was that a old 33' Express Cat race deck that was built for the Smith/Baja family of the late 80's to the early 90's ?
Thats when Offshore Racing was real !!:thumbsup:

[donmac]

I don't know who the boat was built for but it was probably mid or early 8o's when built. I raced it with Jim Brown out of Cleveland. started in "87". If anyone on here know's Jim your a lucky person.

[Vicious]

I don't know who the boat was built for but it was probably mid or early 8o's when built. I raced it with Jim Brown out of Cleveland. started in "87". If anyone on here know's Jim your a lucky person.
Do remember if the boat was a 31' or a 33' I think jim browns boat was a 31' express. Any pics?

[Ted Fraser]

My motion was a LITTLE smaller but I ran the outboard motors 20" lowers with a full blade in the tunnel and the center motor was a 15" lower. Look at the picture and you will see all motors level. Straight line bullet with good accelleration 118 mph

[wideglide55]

Talk to MJWalters on here,his 30 went 117 with 2-stock 99 / 300 ProMaxes.Awesome number with twins on a boat that big.

[donmac]

Do remember if the boat was a 31' or a 33' I think jim browns boat was a 31' express. Any pics?
I have some pics from the 87 worlds and frostbite final in cleveland which we won. It was a shake down for the new engines which finally pushed that hull to the century mark in testing. unfortunately the race in lake Erie was in eight to ten footers, we averaged only 70 mile per hour but a 24 skater averaged only 6mph. I think we hurt one of the engines in that race and it let go at the worlds,maybe not enough break in? only had about 6hours on it. I will have to dig out some pics. to scan. the boat may have been a 31 but it felt much larger. I never measured it just rig and run.

[Brad Zastrow]

Here is the way to rig to run fast. Install the the port and starboard engines so the drives are just tucked in from the tunnel. You want the gearcase covered by the sponson. The props will be swinging into the tunnel. Propshaft center about 1.5" above the bottom of the hull where it lines up with the hull vertically. You can go up and down from there. Water pressure is the issue. Center engine about 2" higher than the outer two. I would suggest hull water pickups and not worry about the water pressure. I lost an engine because at 110 mph cruise in a Poker Run I was making a slight wide turn and did not realize I was losing water pressure to one engine.

Even the big offshore cats are setup this way with twins. The lower units are hidden and the props swing into the tunnel. You want the props at lowest possible point of the boat without dragging the gearcase in the water.

After rigging spend a full day or more of testing. Small 1/8" up or on the engines will make differences in speed and performance. To high and you lose water pressure and/or start blowing out. Three or Four blade cleaver props on the outside engines and some boats run a three blade in the center.

Someday I would like to try the five blade Herring cleaver props the racers are using. I would assume even higher X-dimension with those and even more speed.

[Garmin]

thanks!!

[Maritime_Eng]

Any updates?

[skydog]

yea yea!! Good stuff!!! Boy three motors not much or any faster on top end. So much drag, nuts!

Skydog

[Maritime_Eng]

Is possible to get a 35 Motion to run 100mph with twin 300xs's?

[Garmin]

if getting a 35 Motion to run 100mph with twins was possible, i would do it. no way will it run 100 with twins. the 35 Motion is a big boat, and the third engine is needed for such a boat