Which Volvo Penta D3 or D6 ?

[cudashark]

Dear Forum members.

I would like to power my Cold Molded Wooden Runabout with the Volvo Penta Stern Drive Diesel.

I have had several differing opinions as to the size of engine for what I would like to achieve.

First my boat is 5000 lbs without engines and fuel, people. I estimate the weight "loaded to be around 7000 lbs without engines.

So:

7000 lbs

33 ft length

11 * dead rise

9' 11" beam

I would like to go 50 + knots


I like the Volvo Penta D3 -190 and have been told that they have a 220.

I plan on twin engines. The D3 with drive is only 730 lbs.


Question 2: Is the five cylinder D3 as fuel efficient as D4 or D6. (better than gas)?

[Pericles]

Cuda,

Some old discussions:

http://www.boatdesign.net/forums/arc...hp/t-6927.html

http://rib.net/forum/showthread.php?t=21210

http://boatdiesel.com/Forums/index.c...ID=624&RED=NS3

http://rib.net/forum/showthread.php?t=21625

What about Volvo IPS?

http://www.volvo.com/volvopenta/na/en-us/

http://www.ybw.com/auto/newsdesk/200...42mbynews.html

Regards,

Pericles

[cudashark]

Thanks Pericles,

I've read over the articles you sent and I think I need to concentrate on gas engines instead.

The HP to weight is important to the performance. I'd like to squeeze out every knot I can.

The IPS is interesting however I have configured the transom for stern drive and eventually surface props.

I'm torn on which power package to go with. Mercuries, Volvo what else?

Ray

[Pericles]

Ray,

Is it really too late. http://www.mercuryracing.com/outboards/verado350sci.php

Best of luck.

Perry

[cudashark]

Thats a great outboard but I need to jack shaft the engines forward 42 " to get the cg where it needs to be no to mention the transom.

Thanks Perry

[cudashark]

Hey Perry , how's St Johns Wood look these days> I'm ASL alumni. Lived 250 Finchley Rd near Swiss Cottage.

Ray

[Pericles]

Ray,

Swiss Cottage & Finchley Road are very cosmopolitan. The Met station and West Hampstead station are going to be redeveloped as a massive interchange complex including North London line and a Network Rail commuter line. There's already a super store and multiscreen cinema, but what is worse is that the traffic is heavier and slower.
http://images.google.co.uk/images?q=...=1&sa=N&tab=wi

I do not go there!

http://citytransport.info/PhotoCD/1328_45a.jpg

If you can fit surface piercing drives could you fit these? http://www.ultradynamics.com/

With the price of gas rising, I think diesel has to be considered as you could make your own.

http://en.wikipedia.org/wiki/Vegetable_oil_used_as_fuel

Regards,

Perry

PS

http://images.google.co.uk/imgres?im...icial%26sa%3DN

[Nojjan]

I'm sorry to say but what you are building does not look like a 50 knot hull. At that speed the trim of your boat will be extremely low and it's possible that it will become seriously uncomfortable to operate (if it does not porpoise before).

In any case you might get 42-44 knots with 2xD3-190 (I am not aware of a 220?). And yes the specific fuel consumption (fuel mass per power output and time) for the D3 is similar to the D6 (comparable efficiency), although the engine weight will give an advantage for the D3 given the right boat.

[cudashark]

Thanks Nojjan,

Is the info on the D3 from direct knowledge?

I am hearing a lot of conflicting info here locally.


PS I really enjoyed and miss London.

Ray

[cudashark]

Nojjan,

With regard to a tendency to porpoise; is that not a center of gravity issue. The engine package is going to be jack shafted forward 42 inches from the drive. I plan on using the aquadrive cv system. I want to go diesel but will go gas if I must for the hp to weight issue.

I'm not going to use trim tabs. I feel the degree of trim on the drive will be sufficient.

Any thoughts on this are well appreciated. If I'm lucky I can learn something new every day.

Ray

[Pericles]

Riva boats are famous for their ride and for coming onto the plane with hardly a change in trim.

http://uk.youtube.com/watch?v=bJkF8sAX0NU

http://www.rivarevival.com/boats_for_sale.htm

http://www.rivagb.com/

http://www.classicboat.com/classic-2...r-Aquarama.htm

Perry

[Nojjan]

Hi

The info I claim comes from having seen the normal data sheet on the engines (I don't have them so I hope I have not recalled it incorrectly). I'm sure you can get the normal tech data sheet on these engines if you just ask Volvo (it is something they give out to their OEM's so it should not be a big deal).

As far as the jack-shaft goes I am surprised that you would need it? Moving LCG like that usually means slowing the boat (at least with a low deadrise that you have), unless you aim at a low top speed (which we know you are not).

Porpoising can occur for several reasons, most easily if you have a rocker in the bottom. CG-position is not always the cure for porpoising. The reason for warning you is that I have seen many small flat bottom boats (15-20 ft) that porpoise at higher speeds (low deadrise = low trim) and it has not helped to move CG forward.

Also, in my experience drive trim and trim tabs are for different purposes. The drive trim is used to optimize the thrust angle, the tabs are usually intended to correct uneven load and wind conditions.

BR / N