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Old 23-07-2018, 09:34   #76
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Re: Engine placement at bow

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Originally Posted by Pelagic View Post
I understand and my negative reaction was to your first post drawing, which showed little thought.

Was that George Beuler also?

Beuler's Tasman Sea drawing shows a lot more thought but still a conceptual study and a work in progress.

As a marina liveaboard , with the occasional fair weather cruise, its layout might be attractive, if they were willing to risk being guinea pigs with a far more complicated and expensive shaft system.

Again, would be interested to know if it ever was built for that customer?
No, the first post is by Trevor Bolt, design brief on post #11.
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Old 23-07-2018, 11:56   #77
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Re: Engine placement at bow

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Originally Posted by Terra Nova View Post
In your link the only dubiously "positive" the author could think to mention was:
"...engine in the bow opens up the entire rest of the hull." The same exact thing could be said of a midship or aft engine location, that it "opens up the rest of the hull."

I'm certainly not impressed, in spite of the best efforts of those of you willing to try to make this sound like such a great idea.
I have to agree. A more useful spot for the engine, and which allows more use of the interior, is under a companionway or cockpit where you cant use the space anyway. Taking up the bow which can be an entire state room is not a good use, and as I said earlier just one reason designers dont do it!
The talk about having engine room space to stand up there is mostly bunk also, the bow is very much a V shape and you cant stand there without a raised floor to make it flat.
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Old 23-07-2018, 12:14   #78
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Re: Engine placement at bow

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Glad you ask...

(Disregarding vulnerability of course)
The rest is pretty much irrelevant when you ignore a primary design consideration.

Unlike a plane, it's common for boats to hit floating debris...so unless you build some sort of cow catcher on the front it's not practical for a typical cruising boat and if you did, you would kill the minor efficiency benefits.
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Old 27-07-2018, 09:06   #79
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Re: Engine placement at bow

A lot of people seem not to like this because it is weird. Others for lots of reasons - some valid and others not. Like buoyancy.

When you plunk that boat in the water it will shift until the center of buoyancy is lined up with the center of gravity. Designing is a tedious process of calculating the weights, buoyancy, and the various forces at work - not just in the bow, but in the whole boat - and re-adjusting over and over until you arrive at something that will work.

"Work" means that it fits the client's requirements and will operate safely within the requested cost and operating parameters. (Same is true in any design/engineering project.) If the client is a manufacturing company, conventionality is important. If the client is an individual, they are probably commissioning the design because they do not want something conventional.

When calculating the weights involved in this boat, you might add up the mechanical weight in that space and maybe it comes to 1000#, for example. But remember that you are not putting in the V-berth, the water tank under the V-berth that I see sometimes, the storage allowance under the V-berth, the various lockers and drawers and such (and the load of stuff that always ends up inside of them) that often appear in a forward berthing compartment, perhaps a forward head, etc. So the net weight that the engine adds in the bow will be a lot less than 1000#. Also, that bulbous bow, while it may or may not add efficiency to that particular hull, probably adds some hundreds of pounds of additional buoyancy up forward. Since the entire design is calculated to put the boat in trim and since the net added weight of the engine up forward might be negligible, I don't think buoyancy is really a concern here. And the forces involved might not be affected by that full 1000#.

Other concerns are valid, but can be mitigated with sufficient funds in the building process - such as shaft length. Still other concerns are personal: you don't like the layout, etc. That's why there are many different common boat layouts on the market. Changing an oil filter in a storm is unlikely to be an issue if the boat was not designed or used for crossing oceans.

In the end, the boat does not need to make any of you happy. As long as it is safe for its intended purpose, it needs only to make the client happy. As was pointed out earlier, this looks like a nice Loop boat for an older couple who can't climb or squeeze into a belowdecks engineroom, or just doesn't want to. For those of you who aren't old yet, just wait...
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Old 27-07-2018, 14:23   #80
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Re: Engine placement at bow

Nice balanced post FatBear.
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Old 27-07-2018, 14:30   #81
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Re: Engine placement at bow

Engine in the bow, with the additional weight of a chain locker I think is a is a bad idea.

On a smaller vessel, engine amidships or slightly astern of amidships, where the engine box cover can serve as a table or bench in the galley is a great idea--and a more easily serviced engine.

Of course this also means moving the chain locker aft a tad--or just using a shorter length of heavy chain and a nylon rode on a deck reel, to make the vessel sit nicely balanced fore and aft.

I would not sail without a diesel engine, or two wave proof outboard four stroke engines water-cooled for a small cat.

I like the engine in the galley, or just under the steps down into the hull in the companionway, and a longer propeller shaft properly shielded. further aft makes it harder to reach for routine inspections and makes the vessel ride less effectively when heading into the seas. Further aft means a broader stern, and is more affected by a following sea.

I had a diesel quit through cavitation once on a lee shore in a storm with seventy kilometre an hour plus winds abeam.--I was glad I could reach the engine and bleed the air comparatively quickly. Moral--make sure tanks are always comparatively full with spill-proof vented caps, or better still, always use a header tank.

Quick and easy access saved our lives--there was no way we could have survived coming ashore on those rocks in that sea. As it was--we were within 200 metres of the rocks when power was resumed, and were it not for our mainsail holding together, we would not have been able to claw our way forwards to maintain steering and to keep us away for long enough.

One of the disadvantages of a set well forward furling big Genoa as opposed to a hanked-on sail able to be dropped and stowed completely or removed, is that when in a storm with limited scope for tacking, they provide enough lateral pressure even when fully furled, to overwhelm the rudder unless one is able to maintain forward speed--and the stronger the wind, the more forward speed one needs. We had tried to let it right out, to try to get us a bit more forward speed--but it was just making things worse so we furled it as tightly as we could.
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Old 27-07-2018, 15:10   #82
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Re: Engine placement at bow

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Nice balanced post FatBear.
I tried to put it right at the design waterline.
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Old 27-07-2018, 16:55   #83
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Angry Re: Engine placement at bow

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Originally Posted by Wckoek View Post
Just saw this design and was curious.
Aside from weight distribution and power loss from transmission, is there any reason that engine isn't place in front more?
Seemed like a good way to save space in a small boat.
At the beginning of 1980s I owned a 28' sailboat manufactured by COMPIS in Sweden for some 15 years. She had a Faryman Diesel below the V berth. Power transmission was through two high pressure hoses going to a gearbox under the cockpit connected to the prop shaft. Engine was only responsible for running a hydrolic pump. The gear handle changed the direction of the oil pressure inside the gearbox, therefore no problem in shifting gear to reverse even at high engine rev. It was nicely balanced when sailing especially when the crew were gathered in the cockpit, where they usually do. The only problem I had was the breakage of a pin attaching the driveshaft out of gearbox to the propeller shaft. So I kept a spare one and learnt to change it quickly and painlessly.
The boat became a popular fast racer selling many until the company decided to change to conventional placement of the engine and naturally it went bankrupt.
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Old 28-07-2018, 03:42   #84
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Re: Engine placement at bow

I think it is a daft idea. There is much less buoyancy in the bow and as been said before weight in the ends is to be avoided. The drive shaft and exhaust need to be routed through the boat which will inevitably interfere with other structures.
Bad idea !
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Old 28-07-2018, 15:26   #85
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Re: Engine placement at bow

I like the keel protecting my sail drive and prop and the back wash of the rudder does help for more responsive handling . My guess it is a bad idea for collisions and rough weath think the prop would leave the water every so often not good for engine. Just my thought off the cuff.
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Old 30-07-2018, 00:00   #86
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Re: Engine placement at bow

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I think it is a daft idea. There is much less buoyancy in the bow and as been said before weight in the ends is to be avoided. The drive shaft and exhaust need to be routed through the boat which will inevitably interfere with other structures.
Bad idea !
Unlike a sail boat where we favour a fine entry power boats often carry much of their displacement well forward so I tend to the opinion that weight placement well forward would not be a substantial problem.

The drive shaft arrangement is not a problem it just requires more bits.

Weight in the ends is pretty well always an undesirable characteristic however with the large volumes of fuel and water carried by some vessels and the comparative lightness of some modern diesels one might be able to arrive at an acceptable weight distribution.

Running the exhaust back through the transom using hoses which are then kept from burning up by pumping sea water into the exhaust system on the engine appears to cause the odd problem as numerous post in this forum attest might be considered loopy by the dry exhaust out above the wheelhouse trawler folk.

I think the classic of appropriate vessel design for the circumstances likely to prevail has to be the different outcomes resulting from Amundsen's and Shackelton's choices of appropriate polar vessels. Amunsen's design criteria for a shape which would ride up on top of crushing ice appeared to have a better outcome than Shackelton's choice of a conventional vessel.

I would like to know what the design criteria were before declaring the designer a moron.
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Old 20-08-2018, 09:30   #87
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Re: Engine placement at bow

Guys, reading "Fishing boats of the world" having the engine at front is a more proven concept than we expected.
There is a class of fishing vessel, the "tuna clippers" have their engines in front.
These are extreme vessels ranging from 90 to 160 feet in length, carrying ocean crossing fuel capacity of 26,700 gallons or more with a range of 10,000 to 12,000 miles and able to keep live bait for up to 4 weeks, bringing back 110 to 580 tonnes of tuna.
I guess vibrational problem isn't a concern to these big boats, or maybe dead fishes just doesn't care.
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Old 20-08-2018, 09:33   #88
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Re: Engine placement at bow

Rising fuel cost probably made the fleet extinct.
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Old 20-08-2018, 09:40   #89
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Re: Engine placement at bow

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Originally Posted by Wckoek View Post
...There is a class of fishing vessel, the "tuna clippers" have their engines in front...
Here is a case where the overwhelming need to keep the fish hold clear resulted in an engine location compromise.
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Old 20-08-2018, 10:03   #90
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Re: Engine placement at bow

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Originally Posted by Terra Nova View Post
Here is a case where the overwhelming need to keep the fish hold clear resulted in an engine location compromise.
Is it a compromise ?
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