hull design for both up river and large lakes

[River Cruiser]

I have been trying to figure out the proper hull form for a boat that will be used as follows. Down river on the Yukon River , around Alaska and up the McKenzie River as far as possible. Or vice versa! I am not in a hurry and fuel efficiency is most important.

The boat must be trailerable.

As far as I can figure out a displacement type boat of 28 ft length will go about 1.3 times 5.1 or 6.7 knots or about 7.7 mph at any reasonable fuel efficiency.
There are many places where this equals current speed so my question is

Can a displacement hull of this length make headway against the current and at what cost in fuel efficiency?

[ted655]

Mpre info?
Expected water depth. Rocks or rapids. Cab or open style. Outboard, inboard, I/O. purpose of boat. Material.??????

[PAR]

There isn't an ideal hull type that will address your needs. There are things you can do in the design development stage to increase it's abilities or your concerns.

Narrow, light weight forms will be the most efficient, assuming a reasonable level of acceptable drag. Yes, you can punch through contrary currents and head winds, but usually at the cost of some efficiency.

Then there are the issues Ted has mentioned. Boats well suited to their owners need to fit a specific set of guidelines. Many things govern these, some of which you've indicated. Others such as generally sailing area, type of use, expected duration of cruises, etc. will affect the boat shape, its scantlings and configuration.

How much efficiency will you loose into a 5 knot current (for example) would be application dependant. One boat model may do considerable better then another in this situation.

Are you looking to buy a completed vessel, for this cruiser, have one built or build it your self? If you're looking for suggestions, then several production and semi custom models come to mind. It sounds like you may need a custom or semi custom, if you're in a position to have one built.

I have a few low power requirement designs that might interest you, if you care to contact me through email (click on my name). If looking for a production craft, then can you provide more information regarding desires, wants, needs and just can't live withouts in regard to your next cruiser.

[River Cruiser]

Thank you for the quick responses....more info to digest.
The material will be aluminum plate.
The style will be cruiser style, live aboard.
The plan is to stay in navigable depths of water of 3-4 feet.
Power is reckoned to be i/o diesel capable of 24 hour running.
If there is an available outboard diesel small enough I would use that as a get home engine to avoid duel fueling.
I am able to have a hull custom welded up locally and dropped onto a custom trailer.
I then plan to finish it up myself.

I plan to provide lightning protection, anodic protection and provide for a generator and/or solar panels and inverter for back up power. I expect to need a battery bank of some type for power.
I also need additional fuel capacity for the long runs and extended periods out of port anticipated.

My principal question tho is the correct design of the hull for the up river portions. My preference is a displacement type hull within the waterdepths limits. I think that I probably would need about twice the power for up river as compared to lake and ocean cruising. That brings up the question of what kind of power plant can stay healthy running at extended periods of 30-50% power output.

[ted655]

Look at the hull on this Gibson HB. A Garvey style, it is displacement at low speed but will plain at full throttle.
This particular boat is equipped with a single diesel I/O. It safely ran in 24" of water. It would trim up and "pick" its way in 16".
It is very stable & handled mildly rough water well.

[ted655]

Here is a trailerable size version of the same type hull
http://kingston.kijiji.ca/c-cars-veh...QAdIdZ49758498

[Guest625101138]

If you want to push well above hull speed then you should think about a catamaran. Here is an example of an 8m cat:
http://www.ecocats.com/8mChaseboat/t...1/Default.aspx
Probably faster than you need and maybe too wide for a trailer but the hulls give you an idea of what to look for. You would find a good 8m cat would move faster than 10kts with a couple of 10HP outboards.

There is another thread that has examples of a "monohull" that have very slender underbodies that perform similarly to a catamaran. Have a look through this:
http://boatdesign.net/forums/showthread.php?t=22408
The ASM10 that I sketched up is really a trimaran but it looks like a mono on top view. I think this would be a nice river boat with a little diesel. There are some sites referenced that offer boat plans for something similar.

I am sure you will find plenty of naval architects interested in producing a design for economic operation if you cannot find suitable plans off the shelf.

Rick W.

[kach22i]

If going up river is the main/most important part and plus saving fuel is critical, then you might want to consider a hovercraft - really.

http://www.ushovercraft.com/


http://www.amphibiousmarine.com/

Plans:
http://members.aol.com/sevtec/sev/skmr.html

http://www.hovercraftalaska.com/

Adventure Story...........North to Alaska.
(No water depth charts required)
http://members.aol.com/sevtec/sev/AK.html

[kengrome]

Can a displacement hull of this length make headway against the current and at what cost in fuel efficiency?

A semi-displacement hull might be your best bet. William Atkin designed a bunch of them. The ones I'm talking about are called "tunnel-stern Seabright skiffs". Renn Tolman (Alaskan boat designer/builder) even used the bottom of one of these Atkin-designed tunnel-stern Seabright skiffs on his new Tolman Seabright skiff. It's nowhere near 28 feet long though, so it's too small for you -- but Dave Gerr has a bigger one that might work for you:











Then again, the boat above is probably too big at 34 feet, so here's a 28 footer:






This second one is not a tunnel stern Seabright skiff, but it's still a shallower draft boat than you mentioned in your requirements, and it's the right length. More pictures here:

http://www.gerrmarine.com/