Volvo Automatics for Marine Power.

[Pericles]

A 1991 Volvo 960 3.0L engine with 4 speed automatic gearbox has been offered to me. It develops over 200hp and it has set me thinking if it could be used as a complete unit in a Glen L Ski King or something similar? http://www.boatdesigns.com/products.asp?dept=258

My thinking is that the auto gear box will permit the boat to be over propped, but still not strain the engine, yet at speed the engine revs will drop, whilst the boat continues apace. It seems totally logical to me, but there must be a flaw in my thinking otherwise Volvo would be offering such a system. Good acceleration and overdrive in one package. What am I missing? Comments please!

Pericles

[marshmat]

I'm assuming, of course, that you plan to properly marinize the motor itself.
The value of a 4-speed transmission in a boat is a lot less than in a car. At higher speeds, the boat needs a LOT more power, it can't coast like a car does. 2-speed boxes are common, the low gear gets you up on plane and the high gives you a good speed and RPM range once you're up there. Not sure what gain you'd get with a 4-speed.
You'd probably want manual control of the transmission, rather than letting it shift for itself, and it would take a while to figure out just what speeds and loads to shift at.
I think overall it would add a fair bit of weight for relatively little benefit. But if you carry a wide range of loads at a wide range of speeds, it might help you get up on plane quicker with a heavy load, while still giving you some speed potential when running light.
It'll be a lot of experimentation, regardless of what you do.

[Pericles]

Hello Matt,

Thanks for your reply. The beauty of the Volvo 960 is that it has heaps of torque and it is very good for pulling caravans. The transmission can be locked out of fourth gear and first and second can be shifted manually. The unit is without cost to me, so I have only to pay Lancing Marine for marinizing the engine and yes, it will be an interesting experiment. As the transmission is aft of the engine and we sit on the right to drive, that'll be the helm position in the aft cockpit of the Sea King.

It is because I saw the most fabulous model of a Riva at a model shop yesterday that I got the desire to have a runabout that looks similar. The 15' Crackerbox http://www.boatdesigns.com/products.asp?dept=207 has the style and demonstrates an aft helm position. What do you think of Grazia? http://images.google.co.uk/imgres?im...r%3D%26sa%3DN?

Pericles

[marshmat]

Always take free stuff.
I take it this setup is from a rear drive car, then.... in which case I suppose you could make it work. Is the transmission an electronically controlled type? (If it is.... I'd be tempted to rewire it to shift only on command, sort of like the manu-matic thing that's a notch back from Drive on a lot of new cars these days.) You'll need to figure out some way of forcing it to stay in your chosen gear, or else it'll probably try to shift every time you surf down a wave and start to climb back up the next one.
You'll probably want to be careful in the boat not to push the motor too hard... in a car it'd be near its max output for a few seconds at a time, in a boat it's gotta do that for a lot longer. But I think you could make this work. That 'Crackerbox' looks like an ideal platform for it....

[Frosty]

I for one hope that you do it and keep us posted. It is a question offen asked but as said not with a 4 speed. If it were me I would fit the engine and drive and give it a trial without all the expensive marinisation stuff. You will know immediately if you have got some thing worth the effort of a full marinisation mod.

[Pericles]

Yes, rear wheel drive. The 2 lower gears can be held with the floor mounted shift lever up to full 6000 revs and the throttle pedal will retain the kick down facility to deal with any "surfing", however this boat is for flat calm cruising. Don't want water droplets on the varnished topsides. I am very pleased you think it might work. The hope is to improve fuel consumption and extend engine life. Then of course, these engines can be re-chipped without difficulty.

You can find the build story of another good looking boat here. http://www.glen-l.com/designs/inboard/dsn-genc.html

Pericles

[Frosty]

I think you will however find installation difficult , the length will be a problem. If you look at normal marine transmissions they are short in length. The output of a marine transmission is also low down assisting installation and the all important shaft angle. I hope I dont have to explain that you will also need a thrust bearing on the shaft --again increasing an already long tansmission. Oh by the way your reverse gear will be exteeemely low.

A car auto transmission balances many pressure before making the decision to change up or down. When in Kick down mode there is an increase of pressure to hold the clutches under full load. As you will be transmitting much more Hp than the gearbox will be expecting and programmed to recieve your reults will be interesting.

[Jango]

Keep in mind that Speed in a Boat is a function of HP, together with Weight and Bottom shape i.e. Hull factor. Since HP will not change with the use of a 4 speed trans, max speed will not improve but rather be less with the added weight of the auto trans.

Low speed torque at the prop will however be improved which could improve acceleration. Since the Prop will need to be sized according to weight and max. high gear shaft RPM, the boat will feel extremely Under-Proped when in the lower gears.

Also this Engine - trans combo in the "Crackerbox" will require the CG to be much further forward than desireable causing undesireable operation. i.e. Bow plowing and rear hop.
I would suggest going to a V-Drive configuration - Engine only in the rear coupled to a V-Drive with in & Out gear only (No Trans).
Jango

[Frosty]

Mmm-- a v drive would help in the length problem but it would then need new engine beds and all this extra cost for a project that might not work will end up costing more than a marine job.

I think the prop should be chosen entirely on top gear to Hp output as in a normal installation. My only concern is that the auto transmission will see basically almost full power demand and try to kick down constantly --unless total manual control was acheived over the gear selection. If the trany has a modulator valve I would fathom a way of keeping this valve in kick down mode( high line pressure).

I also think that I might try a way of abandoning the torque convertor, which will be difficult as the oil circulates through the transmission,and will drive the pump. I feel that the torque convertor will generate a lot of heat driving in an almost full power situation.

In a dignostic stall test of an auto transmission (full power application) 15 seconds is all that can be tolerated with out over heat.

I was thinking about this project yesterday while following the wife around the supermarket and I think that some one must have tried this before, and if so why have we not heard of it?

[Pericles]

Hello Jango,

There are other photos of Crackerboxs on the Glen L site http://www.glen-l.com/designs/inboard/dsn-cbx.html that show the midships position of the engine. The weight factor is much less than you would suppose as the unit that powers the Volvo 960 is an in-line 6-cylinder engine. This advanced power unit features an aluminum cylinder block and double overhead camshafts allied to 4 valves per cylinder. This engine represents the first stage of an entirely new generation of in-line engines for Volvo vehicles. Development of the new series of 4-cylinder and 5-cylinder Volvo units came into being because of these pioneering devices. It's a unique motor and can be re-chipped to 300 hp.

The auto box is also light in weight. First & second can be selected manually, third is selected when pulling loads by preventing the upshift to fourth. As the Crackerbox is 15 feet long and only needs 100 hp, I must increase length to 23 feet and beam to 8 feet, but it will be a Ski King lookalike with aft helm position. http://www.boatdesigns.com/products.asp?dept=258

I have discussed marinizing the cooling circuits and exhaust system with specialists and they say if the auto box will not work, the bell housing can be machined to connect with a marine gearbox, leaving just the need for a lightweight flywheel. This is all getting away from the original concept. I am going to write to Volvo UK for their suggestions.

Pericles

[Jango]

Hello Pericles,
While decreased motor/trans weight is a BIG plus, the concern is location of CG. (Fortunately rear passenger placement Helps alot)
Since your drive consists of a angled drive shaft, probably at 14 - 16 deg. The forward thrust Also has a Vertical component which wants to raise the rear of the boat, causing Bow Plowing and bounce.

Many years ago, I raced in the Crackerbox Class and I have expierenced these problems. With One person only in the boat, the ride was Wild. Check out the motor/trans positioning on paper before you commit to a design. Obviously, the Longer the boat, the less potential problem. I might add, you may not need an extra wide Beam, since total weight should be minimal. Less wetted surface plus less weight equals more speed.

Should work out OK, if you get the length to 18 - 20 ft plus.

Sounds like a Great Engine

Jango

p.s. I built the GlenL "Monoco" - Great Boat and excellent plans

[Pericles]

Hello Jango,

With a transom drive/surface drive, the prop shaft angle is 8 degrees, not 14 to 16 degrees, so much less vertical lift at stern. I think the same engines are available in the US.
I have also been looking on the internet in UK for a manual gearbox 960, without luck so far. However, the Volvo 940 was fitted with a 2.3 litre,low pressure turbo, 4 cylinder engine. I drove an estate version for 2 years and had it re-chipped to 240 hp. These cars were mostly manual shift and are plentiful and cheap here. Depending upon Volvo's reply to my letter, a 5 speed manual gearbox with the turbo engine might be quite a laugh. I would have to transfer the clutch mechanism into the boat. Drive just like a car, except no brakes.

Here's another idea. The Volvo V70 is front wheel drive, so how about a side wheel paddle boat? Granted you would not have independent drive to each paddle wheel, but combining the paddle wheels with road wheels would create a craft that launches itself. Mount engine, gearbox and drives shafts midships, another slim wheel aft in a rudder shaped housing and there is a boat of distinction and panache. Down the ramp, off to sea, return to port, drive up ramp and park in boatyard.

Oh dear! There's a knocking at the door and I can see three men in white coats coming to take me away.

Pericles

[Jango]

I believe the GlenL plans you cited, are conventional Inboards, Not Surface Drives. No expierence with Paddle wheels. Good Luck

Jango

[Jango]

Forgot to mention, an Alum Blk, Volvo 3.0 DOHC at 401 lbs is not exactly a liteweight, - about 40lbs Heavier than my Ford 5.4 Iron Sm Block which is producing over 450 HP. ( Ford sm blk V8 w. Alum heads - without marine manifolds or trans - 360 lbs)

jango

[Pericles]

Decent V8 motors are rare in the UK. The are V6s aplenty, many are Renault units as fitted to the Volvo 760. Only 165 hp, hence my interest in the 3 litre straight 6. I have been informed that the marine cooling circuit does not present any problems as the existing fan belt setup can drive the raw water pump.

The only concern seem to be the fire risk from the exhaust manifold before the water injection system is fitted. With a beam of 8 feet the engine room bulkheads and hull sides are well away from the motor and a bit of strategically positioned "dry wall" lining might not come amiss.

I read the postings about using the Flex Plate instead of flywheel with interest, because if a marine transmission becomes a necessity!!!

Pericles