Engine placement at bow

[malbert73]

For all those who discuss filter changes as an issue- no reason a pair of primary fuel filters can’t be mounted in series midships in a locker near fuel tanks. Make first a 30 and second a 2 micron, with an electric boost pump, and you’d never need to enter the engine room to change or monitor filters. I actually think in a powerboat the noise reduction and heat reduction would be a huge boon to the design. You could sit in main salon or aft deck and not hear much of the engine. Otherwise weight placement is the main issue for me.

[RaymondR]

Ah Peelagic,

The point I was trying to make was that designers often move away from the orthodox for perfectly valid reasons. The Israelies to preserve valuable crews, the "Emma Maersk" is owned by a shipping company which operates a large fleet of vessels and has been around for about a century and consequently probably knows what they are doing.

I am old enough to remember when all formula 1 race cars were front engined and no one builds them any more, and I'm sure that if I put my mind to it I could find many more examples.

I would want to have a bit of a yarn to the designer as to why he thought it was a good idea to put the engine in the bow before going rabid with my criticism.

[Cheechako]

Originally Posted by thinwater

No longer than the shaft on a bus. Different engineering, no point in commenting without seeing the details.


One obvious result is a low shaft angle.

Actually, long drive shafts are usually broken up in to multiples . "Whipping"

[Cheechako]

Originally Posted by RaymondR

Ah Peelagic,

The point I was trying to make was that designers often move away from the orthodox for perfectly valid reasons. The Israelies to preserve valuable crews, the "Emma Maersk" is owned by a shipping company which operates a large fleet of vessels and has been around for about a century and consequently probably knows what they are doing.

I am old enough to remember when all formula 1 race cars were front engined and no one builds them any more, and I'm sure that if I put my mind to it I could find many more examples.

I would want to have a bit of a yarn to the designer as to why he thought it was a good idea to put the engine in the bow before going rabid with my criticism.

I think the real point is that designers MOST often dont move away because there are valid reasons not to. But on occasion they do. Often because new technology arrives to support an idea that may have been non useful before. There's a reason most things are the way they are. What people will buy, experience and science. There's a lot of "out of the box " thinking that the majority of people don't want.
Try selling composting heads on production boats.

[boatpoker]

Logan 33 ..... google it.

Lovely, well built little boat with the engine under the v-berth.

[Sailorbob8599]

Originally Posted by Terra Nova

The ridiculously long prop shaft would create vibration problems.

I admit I haven't read pages 2;3 & 4 so maybe another response has covered the matter of drive transmission. I would think anyone designing such a 'different' type of propulsion system would likely choose to design a hydraulic drive system. Seems logical to me, although I've never actually seen such a system on a boat there are instances in other power applications.

[darylat8750]

I would think that the length of the drive shaft is a minor problem that is routinely dealt with in trucks. In a long range boat the fuel could be on the center of gravity. Many boats carry more wt. in fuel than the wt. of the propulsion engine.

I don't have much enthusiasm for dry exhausts or a "North Sea" type of exhaust exiting in the forward 25% of the hull.

The Logan is a nice looking boat but I have zero enthusiasm for a berth over an engine.

[Wckoek]

Originally Posted by boatpoker

Logan 33 ..... google it.

Lovely, well built little boat with the engine under the v-berth.

It looks great, I like the 20's style raised deck cruiser look, and from the specs it must be a good and efficient boat to run too.

I wasn't too keen at the idea of having an engine under the v berth as well, but in reality we only use the v berth at anchor and couldn't imagine using it at sea, so it was a good use of space in this case.

[RaymondR]

Originally Posted by Sailorbob8599

I admit I haven't read pages 2;3 & 4 so maybe another response has covered the matter of drive transmission. I would think anyone designing such a 'different' type of propulsion system would likely choose to design a hydraulic drive system. Seems logical to me, although I've never actually seen such a system on a boat there are instances in other power applications.

With modern hydraulics these transmission systems are remarkably simple to implement and appear on a wide range of mobile equipment. Probably the simplest would be a reversible flow axial piston pump driving any type of hydraulic motor although the gerotor types are fairly ubiquitous due to their high torque at low speed characteristics.

Whilst the power losses in a gear driven marine transmission tend to be minimal compared to other transmission systems we may see more hydraulic systems of this type in the future because with computer control the fuel economy characteristics of an engine and power demands of the drive system can be almost perfectly matched.

[Cheechako]

I have long wondered why hydraulic transmissions haven't been used more in boats. The answers I usually get are they are power hungry, require a lot of cooling. They would sure allow you to locate the engine anywhere you want though. That hydraulic fluid squeezed at high pressure through various orifices creates a ton of heat.
My Maintenance guy in the 200,000 sq ft factory I managed had a saying though: "If it ain't leaking... it ain't hydraulic" I will say most fishing boats I was on had hydraulic winches etc, and most items had a slight wetness everywhere. Not a leak per se though.

[SailRedemption]

Shaft vibration should not be a concern, technology has solutions for this. Cv joints, shaft bearings, etc. I worked on a 280' OSV that had forward main engines it had shaft bearings down through the middle in the tank farm, to shaft generators for the tunnel thrusters, then to the variable pitch props.

With a cv joint and thrust bearing on the engine side and another set on the prop side the vibrations should be less than your normal engine setup with a shaft connected directly to the engine.

I'm not saying it's the best design or the worst but shaft vibration isn't the number one flaw.

[darylat8750]

Originally Posted by Wckoek

It looks great, I like the 20's style raised deck cruiser look, and from the specs it must be a good and efficient boat to run too.

I wasn't too keen at the idea of having an engine under the v berth as well, but in reality we only use the v berth at anchor and couldn't imagine using it at sea, so it was a good use of space in this case.

My objection to the engine under the v berth is heat. I seem to want to bed down shortly after arrival at an anchorage and the engines seem to take a long time to cool down to ambient temp.

[Perfusser]

I have a 1985 Tasman 26 which has the yanmar 10 under the v berth. The prop exits behind the fin keel, which means it is very well protected, and there is no prop walk. The engine is very easy to work on- however moving bedding and mattresses etc is a bit of a pain.

The Tasman is a bit wider than other 26 footers I have been on, with a fair degree of tumble home. Possibly designed that way to overcome weight issues.
the beam necitates getting some heel to overcome some of the water resistance, particularly from waves and slop.

She was designed by Joe Adams, who was trying something to overcome some of the IOR ratings. I am not sure how successful he was in achieving his goals.
I have yet to race her against other 26 footers like Endeavours, which are of the same era. I will need to continue updating the sail wardrobe and put a folding prop on to be competitive.
cheers

[Pelagic]

Almost everything has solutions, but that is not the point, or even a supporting argument.

When suggesting something quite radical, you weigh the technical pros against the cons in comparison with traditional solutions that 99.9% of builders and owners have studied and accepted.


Ignoring special purpose crafts and simply designing for a 45' Trawler, suitable for cruising with a 2 to 4 person crew ...

WHAT ARE THE SPECIFIC BENEFITS OF THIS PROPOSAL, THAT JUSTIFIES REINVENTING THE WHEEL?

[darylat8750]

Originally Posted by Pelagic

Almost everything has solutions, but that is not the point, or even a supporting argument.

When suggesting something quite radical, you weigh the technical pros against the cons in comparison with traditional solutions that 99.9% of builders and owners have studied and accepted.


Ignoring special purpose crafts and simply designing for a 45' Trawler, suitable for cruising with a 2 to 4 person crew ...

WHAT ARE THE SPECIFIC BENEFITS OF THIS PROPOSAL, THAT JUSTIFIES REINVENTING THE WHEEL?

The only things I can think of is that the engines on my boat are located at the point of least motion. It may be possible to use that point for helm and perhaps a sea berth. Also keep the vertical center of gravity lower than some designs?