Cruiser design poll...

Welcome once more Nemo!
One of the reasons that I suggested outboards (apart from those already listed) is that there are thousands of boats already out there with the sterndrive / inboard / v-drive configuration. Outboards, however, have really only ever been used widely by the Americans in powering go-fast fishing machines. With the recent advent of big 4-strokes and dfi 2-strokes, I think that the day of the outboard powered cruiser is just around the corner - so why not ensure that our project boat breaks some new ground?

p.s. Jeff, thanks for the tip on how to post links - I'm still rather new to all this stuff.....

 

Hi,
I just thought about inboard/outboard propulsion (let's forget about inboard) because it seems to me that's the trend nowadays, looking around boat shows.. talking about economy, inboard/outboard gives you the possibility to use a Diesel engine, and you know Diesels are reaching very high specific power.
An inboard-outboard is not do different from an outboard, in terms of draft, trim control.
Another reason, less technical, is "aesthetic", I prefer to see a transom free from one or two big engine carters.
This is just my opinion, I woud be happy to carry on the outboard project as well, if someone else vote for option 4!

Dul, I live near Genoa, on the North-West Coast, maybe you've heard about Portofino, I live in the neighbourhood, anyway, not far from Cote D'Azur

 

I agree about liking a clean transom.

But a Diesel would add a lot of weight, no?

Or is there such a thing as a light weight Diesel?

 

For a stern drive alternative that is still light weight, how about a Rotary engine like http://www.rotarymarine.com/

Are these fuel efficient? Are they quiet because of low vibration and no reciprocating parts, or are they loud because of their higher RPM range? I have not seen one of these, but my guess is that it would be a less likeable sound like an outboard vs. an inboard, but with some engine insulation it might be nice and quiet.

 

rules ... what rules???

Jeff - spot on about the alternatives!

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is that it just depends on whether you can sell that alternative as either better or equally meeting the primary goals of option 4:
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Nemo and anyone else - if you want to change something - just convince the majority...

Good luck with it!

Cheers

Paul

 

My Vote...from Canada's West Coast

...is option #2. Tough, comfortable, maximum 11 knots, ideally aluminium hull, single diesel main and gen-set (possibly with a "come-home" arrangement). Our waters are prone to flotsom/jetsom from logging operations and our tides and resulting currents can run 10+ knots is some passages, hence metal, protected running gear, sufficient power (in an easily accessable engine compartment) and exceptional ground tackle (all chain plus back-up). A vessel in the 38' to 45' range adequate but 50+ would be nicer. Further, because of extended cruising where few facilities exist, outside of the southern portions, self sufficiency for 10 - 14 days is required for fuel and stores. And because of my personal preference to seek out peace and quiet, a large battery bank and hearty inverter when swinging on the hook...also a preference. A pilot house large enough for the helm and seating/dining area, good fenistration (windows/ports for viewing), access to side decks, excellent forward visibility. Would consider para-vanes or fixed keelboards for reduced rolling but not internal/gyro stabilizers...they wouldn't last a season! For our limited number of sunny days or piloting in close quarters, a flying bridge with duplicate/remote instruments & steering is required. Year around operation is anticipated so good insulation, ventilation and heating necessary...but not A/C. For re-sale, chases for A/C "plumbing" should be installed, just in case ever required. Only one master stateroom and one head with separate shower stall required. Any guests would be put up in salon or pilot house. Never-the-less, room for entertaining 6 people, comfortably, is required. Ideally, the engine and gen-set would be fresh water cooled...keel coolers and/or seachest...with dry exhaust with extensive insulation for heat and noise abatement. That's my dream boat if unilaterally powered. I'm playing with the idea of a motor sailer that has many of these qualities. Cheers, Richard.

 

My choice of a transom mounted outboard is based on practical concerns. I started out with the outboard inside an open transom so that it was not visible. Eventually, the aesthetics could not offset the negatives of loss of cockpit room, poorer steering (especially around docks) and loss of buoyancy. Besides, it seems more honest to put the outboard engine where it belongs. The appearance of an outboard on the transom does bother me at all. Maybe it's the form-function thing but it just looks logical.

I/O's are very popular. They appear especially popular with repair facilities since everyone I know who owns one has had mechanical trouble with the complex drive system. Another problem is corrosion and fouling since the foot does not raise completely out of the water.

I saw a couple of the little rotary inboards at IBEX last year and they look pretty neat. Small and light for the power output but the drive system was not there. I tried to get some fuel use figures, but could not get anything nailed down. As I remember, fuel economy is not a strong suit of the rotaries.

In my opinion, the transom mounted outboard best fits the outline of option 1. Availability, service, waranty, performance, cost and reliability all seem better suited than the other choices.

 

building a cost effective boat?

Hello All (welcome to those of you new to our madness)
My 2 cents on the outboard and the fans of option 1
I myself would lean towards the I/O For eye appeal. Yanmar makes a line of small "lightweight" diesels But i like the Volvo Duo-prop outdrive "great low end"
But..... The option 1 crowd seems to be looking at the cost factor and the ability to backyard build. The outboard presents a-lot of great qualities to this type of vessel First is the cost, MUCH CHEAPER to install and maintain.
I have priced a Lugger diesel w/ gear @$27.000 175hp
you can buy a lot of outboard for that!
A good outdrive with a gas motor @ 200+hp will easily cost $12.000 and up
Anyway enough ramble. I think if i were to build or design a option 1 boat i would steer toward the outboard for cost and simplicity reasons!

 

You're probably right on draft, but as tom says, outboards typically require less maintenance.

Another neat thing is that a friend repowered but then rebuilt his old outboards so he now actually has a spare set of outboards. If the motors on his boat act up during the season and require a time consuming fix, he can just swap them in a few hours and be up and running that day... then fix any major problem when he has time. This isn't really applicable to this thread, but it's a nice option he has

 

I vaguely remember hearing that the Mazda car engines were not fuel efficient a long time ago. And on their site they stress fuel efficiency through weight savings, but don't mention any figures, which leads me to believe you are right. Might compare favorably against a big block stern drive because of weight savings in a particular hull, but probably not against an OB.

With 4-stroke outboards now, are there any remaining environmental concerns vs. a gas or diesel inboard or i/o?

 

I'm surprised that it made such a noticeable difference in steering response. I would have thought it would be very similar to what builders such as Four Winns are doing with their swim steps integrated into the running surface. Although their "active after-pods" which "assist in planing" (which makes sense) break free once you're on plane, at slow speeds they would seem to function just like your original setup. Is there any difference? Has anyone read or heard any negative comments on how boats with these running-surface-integrated swim steps handle at slow speeds?

 

And I'm still not 100% convinced that the transom has to be where the outboard belongs. After all, v-drives put the engine aft while it really 'belongs' nearer the CG for better balance most times. The question might be: does the form have to follow the function of every single component, or can the form follow the function of the whole design. I suppose there is a certain falseness to covering an outboard up when it already has a shell, and there might be issues of airflow, etc. But I don’t know if putting an outboard in a box is all that more “false” than the whole idea of a stern drive… maybe it’s just a hybrid step. Moving an outboard forward could:
1.) free up the transom
2.) increase safety if the boat were used for watersports
3.) reduce noise if the enclosure were properly sound insulated, though the echo effect of the enclosure could be a problem too…
4.) improve the appearance

 

You bring up some good points. The engine in a slotted bottom is very common here on the North Carolina coast with fishermen. It clears up the transom for nets, etc. In my experience the engine in a slotted bottom increases turning radius quite a bit whether at speed or around the dock.

The planing "pods" are something of a mystery to me. Perhaps they help get a heavy boat on plane when the trim angle is high on acceleration. On a properly designed light boat, they would never come into play since the trim angle would stay too low for them to be effective.

>Moving an outboard forward could:
1.) free up the transom -- Yes it would but I don't personally mind the outboard being on the transom.

2.) increase safety if the boat were used for watersports -- True, but I don't think that use rates very high on the list of significant uses for a cruising boat.

3.) reduce noise if the enclosure were properly sound insulated, though the echo effect of the enclosure could be a problem too -- Perhaps, but I doubt it if the engine on the transom is shrouded with a proper box.

4.) improve the appearance -- Perhaps, but it is a subjective opinion.

I expect that the design of Option 1 will work with the engine in either location, so it's not a big deal anyway. Moving the engine forward into a box also moves the exhaust outlet forward.
Sometimes it causes a lot of trouble in both aspiration and exhaust fumes. Often, an inlet fan or larger opening has been needed to eliminate these problems

 

Extension..

...of the poll. Since there is not a clear winner yet, and the votes are still coming in, the poll finish date has been extended to this Wednesday.

(Thanks to Jeff for the tech side of that)

Cheers all

Paul

PS Re the inboard/outboard discussion, I would like to add my.02 Euro's worth in that in Europe the fuel cost for gas(petrol) Vs diesel are much more significant than in the USA and from an economy point of view - depending on the use, - the additional initial expense of a diesel could be paid for in a couple of seasons use.
Then again for home build what could be easier to install than an outboard.

 

Yes, the difference between petrol and Diesel is significant in Europe. Actually, almost every inboard here is a Diesel engine. I think those engines are also more reliable than gasoline ones, especially Volvo Penta and Yanmar.