staggered engines
 

I am getting a new boat and have the option of staggered versus side by side engine set up. Looking for input on the trade offs like handling, rough water capability, speed, manueverability around docks, room to work on engine maintenance etc.

Re: staggered engines
 

What make,size & power ?

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Staggered: Faster and easier to bang up in and around the docks.

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staggered: if you have the cockpit room, better balance, drives are lower on the vee and much easyer to work on the motors

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I am getting the first new larger Sunsation. It is now slated to be right at 43 feet. They just added another foot to the engine compartment to accomodate staggered. So there is no impact on the cockpit size.

I'm getting 525s put in it. I haven't decided whether or not to get ITS yet. There is more information on a thread in the Sunsation forum named when is the new 38 coming.

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Staggered lowers the motors in the hull. This lowers the center of gravity. This theoretically makes the boat handle rough corners better and safer with less tendency to roll to the high side. Can also have taller intake setups without having to add scoops. Oilpans are same distance from the hull bottom, so you still have the same access underneath the motors. These are all desirable qualities. Saddle tanks, though, can be high enough to offset this benefit.

Staggered moved roll mass closer to the center of the boat. The roll axis runs from the center of the transom to the nose. The closer the mass is centered, the less roll inertia it has. So what does this do? On one hand, a chinewalking issue will have less inertia, and less tendency to amplify. On the other hand, less roll inertia will allow the hull to rock side to side more aggressively in cross chop. In many cases, though, staggered setups also use saddle tanks. Saddle tanks will add roll inertia, which reverses the above tendencies.

Moving one motor forward moves the center of gravity AND pitch axis forward. Boat should plane easier. Should mow down chop better. Should fly more level. Depending on the need for bow lift on a particular hull, this may NOT result in the best ultimate top speeds for that hull. Also, motor access is fantastic on the INSIDE portions of both motors. The outside portions may be restricted by saddle tanks. You can access the front of the forward motor from the side, and you can access the rear of the rearward motor from the side so it's a win win. Depending on which motor is forward, you will either have excellent or typical (pitiful) access to the rearmost starter. "Easy to remove" tailpipes on the forward motor are a great idea for some more involved servicing on the rear motor..

Having the drives close together supposedly improves prop bite in cornering.

It also requires that you dock it more like you would handle a single. Drive leverage for spinning the boat with opposing thrust is minimal at best. But that is part of what makes them cool.

Oh yeah, staggered is cool. That's a plus.
You do lose cockpit space, but you gain some pretty impressive storage in the engine compartment (think in terms of those greeat big Rubbermaid storage bins).

ITS?
For less money you can do Imco boxes at 12" setback instead of the 7" ITS setback. You still run a tie bar with ITS so you don't really clean up the tail THAT much with it. Your choice.

There's my 2 cents.

mc

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thanks MC, great information.

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Interesting MC... what is your take on Nigel Hook's "tandem" set up in the lucas oil boat?.......... :confused:

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That is one of the best paragraphs I have read on this board in a long time MC Well said. NK :drink:

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anybody have pics of that setup? i have heard Pat W. talk about it on the board here and it sounds very interesting.

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I like staggered better.

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I think I have a few pics.... lemme see........ :D

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Oh, a staggered driveline (forward motor) won't bolt up properly to an Imco box due to lack of inside support bearing. Would require custom jackshaft.

Staggered driveline will work just dandy with a Stellings box.

Not exactly sure how it is handled with the forward motor and the ITS box...

At any rate, it shouldn't be a huge deal to make any of the three work with a staggered setup.

The Weissmann inline setup boasts some even cooler techno points. The "reversed" engine cives a true counterrotation of the crankshafts which truly cancels the engine's torque moment. Most conventional sterndrive installations still have the engines both rotating the same direction, even though the props spin opposite. The weissmann allows standard engine rotation (which allows standard camshafts, standard windage trays, standard oilpans, standard piston pin offsets, etc.) yet delivers the power off the "wrong end" of the motor for true counterrotation.

Also the transmission and drive setup REALLY let you lower the engines all the way to the fiberglass for some record setting low CG ability.

Aside from that, the Weissmann drives are the just cool. I'd love a pair.

BUT - the Weissmann setup adds a full foot or more between the two motors, making it an application that can only be considered sensible in a raceboat. First, you still have the transom hardware for the drive inputs. The "belt dies" of the rear motor must be forward enough to clear that crap. Then you got bellhousings on the motor and then the weissmann U drive and Z drive combo thingy. This booger has GOT to eat up at least a foot between the bellhousings, maybe more. Then you got a bellhousing on the back of the front motor and it goes forward from there. This is a LOOOONG setup. And routing exhaust thru the transom would be "interesting".

I think a more conventional TWIST on the reversed motor idea is to simply turn one motor around "wrong way" and use a snout coupler similar to those used on some of the old Vee drive drag boats. This would allow you to still snuggle the motors closer together, cram the rear motor against the transom plate, and pull the backseat bulkhead all the way up to the front motor's abbreviated bellhousing. No need to leave room for belt maintenance and power steering, etc. Sumpin to think about anyhow..

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thanks Reed, i have never seen a pic of that. actually kinda looks like a pulling tractor in that pic :D. that is some serious access to the motors with that setup :cool:

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Here are some other pics of the drive system.... cool stuff......... :D

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I think taking the power off the engine at the nose would add just as much space as all the Weismann doo-dads.... then you have to pull the engine to change a belt... and how do you hook up the trans?.... and how do you drive 500 horsepower through a keyway and the front of the crank... I guess you could have a special crank made... but talk about huge money...... :eek:

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Reed, they are back to back, one engine is flipped around. Nothing fancy.

Looks like Nigel likes the drives too.

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Yeah.... I've also noticed that Teague stickers are absent from his boat...... anyone know the story?............ :confused:

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Quote Ron P: Reed, they are back to back, one engine is flipped around. Nothing fancy.

I know that.... MCollinstn was talking about taking the power off the nose of the crank... not me........ :eek:

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My bad. :bunny:

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Excellent stagger post MC ! Just to add a couple of notes, stagger's allow ya to run faster with less throttling in a chop as they don't unload the props as often ( easier on drives ) they also fly straighter when coming off of confused waves as they tend to unload together reducing the twist or roll as one unloads later. On the saddle tank front we were able to reduce the roll effect by keeping the tanks low and contoured to the hull bottom for the most capacity, they're under the diamond plate below and hold 75 gal each.

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Awesome post guys!

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WWon, HUGE thumbs up.

Reed,
I agree about the weirdness of the backwards motors, but I've seen a bunch of em in old vee drive and straight IB drags. (usually no belts, no accessories). As with most unconventional installations, there are pros and cons.

I'll find pix.

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Will the big Sun be a full stagger of just a partial stager. I thought I read in another post that it was just going to be a partial stagger. You really don't get the full benefit with partial because the drive lives are still the same. Right?

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Wow! Wicked one... that is one super sanitary engine compartment... I can see there was lots of planning in building that!... Good job!........ :D

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Wicked Won, Clean machine!

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The new Sunsation will be partial staggered. I believe that is pretty much how most of the staggered setups are. My understanding is that takes the drives from about 3 feet off center to about 2 feet, so it moves the drives about a foot closer together.

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Allright now you're just showing off. :cool: NK


BTW My engine room would look as clean as ww's too if I never went boating. :rolleyes:

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I know this is off the subject but I will add a few things.
Mcollinstn did a great job on describing the set-up the only thing is the motors face flywheel to flywheel, The power is taken from the flywheel. The system is automatically counter rotating when the motor is installed backwards.

I changed water pumps on nigels boat and it was not that bad. The serpentine belt is a pain but to re-install when the motor is warm but cold would have been a breeze.

The photos Reed showed were of the Fountain project with the #6 drives. We ran a very tight centers on that one. Nigel does not run the rear boxes, just straight into the WSD drives.

The distance between the flywheels is being reduced. It is now 15 inches. We redesigned the dropbox/FNR to shorten the distance. Most of the room was needed to clear the double cooler bellhousing. We are now making a purpose built housing to accomidate our dropbox system.

The whole set-up was put into a standard staggard engine bay. The motors in-line it now allows us to use the waisted space that the engines were using up. We are working on a purpose built boat to show off the entire set-up. The exhaust will merge just after the rear motor into two (one port one starboard) tail pipes at 6 inch dia. It should sound pretty mean.

The boat inside is about real estate. side by side (SBS) more room Aft cg and high cg. Saggard less room better high speed handling fore cg and lower not so great low speed. Wider centers (SBS) better control around the dock.

Weismann In-Line, the best of both worlds and then some.

pat W :D

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I spoke to Pat once about coming down and looking at your stuff... but I can't ever seem to find the time and Costa Mesa is a little off my beaten path... :(

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Too Old,

Clamps inside of WickedWons are holding all the Cables.
Throttles, tabs, tranny's drive indicators etc.

There not really a pinch clamp, actually machined to fit
the number of cables running through them.

More like a C-channel with a top cap or side cap in this case.

Then held on with two cap screws, simple nice and clean
set-up. And made of aluminum I believe.

Cougarman

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What a setup!
Glad to see the power is taken from the flywheel end. That is why the rear crankshaft bearing is large and the front one is small.

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We were out yesterday in NK's rig in 3-5's and I was amazed at how hooked up the props stayed...with the staggered and boxes he could continue to throttle where my side by side would be grabbing air...like WW says, fast in the rough and also easier on the hardware...win win combination.

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does anyone know if a ts tg can be rigged with staggered --partial/full with ssm's???

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Suuuuuuuuure.... How much money do you want to spend?......... :D

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Just curious about 1/2 stagger vs. full stagger???

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I am by no means a knowlegeable person about staggered, clearly since I am the one that started this thread with the question. But my understanding from the guys at Sunsation is the difference is in just how close the engines are aligned with the centerline. By that, a full staggered setup has your engine more closely aligned in the middle of the boat, and a partial staggered has less overlap in the alignment, therefore the engines are a greater offset from the centerline. My understanding is in the full staggered setup you can get the drives even closer to the center of the boat than you can with partial staggered.

I appreciate any input from those that know more about this than me.

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Mentalpause-- You are correct with your description. I believe the key reason to go to a short stagger is to get more weight forward in order to help 'fly level'.

Chris-- it was said in the 'cafe vs. TG ride difference' thread that there would not be enough room once the trannies were in place to go to a partial/full stagger. I do not know myself as I have not measured it.