Simple Steps

That's lots of boat. Nice modern lines and a good bit of element protection. Can you stitch & glue or are you going to have to go to a frame? I ask, because some of the lines look quite intricate.

 

Really good question,

Here are my guesses.

For the basic hull shape I'm trying to keep it as simple as possible. I'll overlap the the chine and below that is a add on lifting strake. I'm hoping the the bottom hull would get good continuity from a good stringer system despite the step. So in essence it is mating of two conventional convex shapes. It would be built in an upside down jig, or basket mold.

The scalloped and non straight gunnel or sheer top clamp (?) would be done with laminations.

The cockpit area I was hoping to do with layered 4mm plywood or aircraft plywood. Fiberglass covering would provide most of the strength there, with primary structural strength coming from the aluminum cage. This cage connects all to all the surrounding structures. Of course any advice on the best way to mate this to aluminum in a final stage would be helpful.

For the lift up deck portion. I considered shaping pvc foam with a good lamination and supporting structure. This will seat in a verticle tongue and groove if that is the correct terminology. The canvas will have a runout aft if any water does get past this coupling.

To some degree I'll find out when I build a 1/10 model prototype. Any criticisms welcomed.

I will say this does appear complicated but if I can pull it all off it would make an interesting boat.

 

Amidst all my current challenges I'm wondering if I'm biting off more than I can chew here.

In my mind (worry here) it all seems very doable but a challenging undertaking of time. I have a 25' x 25' barn of course I'll have to spend $1000+ to finish it out enough to work in .

I'll have some assistance but largely be building this on my own. I'm at the commitment point so I'm looking for feedback good or bad.

Thanks.

 

Leave the doubt to others.

For a long period I thought that I could "make due" with a Mertens or Devlin design, but that's not what I wanted. If somebody already had the plans for your dream boat - that's where you'd go - but they don't!

If you have an major obstacle - take a long shower or interstate drive and the solution will present itself (okay, maybe not the solution, but a solution). The remedies of technique & tools you'll develop will be bordering on genius.

For me, I think I will have a big dumb when Bill the Cat is finished. It's the learning & the doing that is the most fun and rewarding. But then trout baked with lemon and onions will have to be my solice.

Remember, there are living relatives of people in Ohio who had said, "Orville, you better stick to bicycles, that thing ain't never gonna fly!" They are buried in Ohio and the Wright Flyer is in the Smithsonian.

Good Luck
David

 

Great words and sentiment.

Of course you probably figured out Jacques was the source of a lot of the basics. Keeping things simple enough for builders is an art in itself. I scaled the 19 ft classic probably rather have done the same to the 21 but recreating everything took a bit of time in Rhino.

You're completely right about designing to your own specs. Up here getting around to prime spots presents problems with ferries, accomodations, traffic, etc. While this setup won't do everything, it does give the features I need with a bit of style.

Read your mention about 50hp. Just bought a new 50 hp honda this year for my recently restored 68 whaler sakonnet. Perfect power for just me and perhaps one other. It used to have a 115 evinrude.

[ an interesting aside a couple things just occured to me. never performed as well as it should have with power to weight. Perhaps because it was designed with a lot of wood forward, probably 150 pounds. My dad set the console further back. The end result he used fixed trim tabs. My father was a mechanical engineer from Texas A&M. Did a study on whether rabbits were as manueverable with hard hats (made out of cut tennis balls) ; ).

This fixed the trim angle at moderate speeds but as more power was applied it met with more resistance. One individual asked me why the front was pitched a little high. Missing a 100+ pound of teak.]


I'd imagine with the weight you have it would be a good match for your flat cat. Of course you might want a four blade prop to get you on plane faster since you don't have as much planing surface for lift. Just guessing.

Here is a picture of half cat with step, (twin sponson whaler design) ; ). The console is my poling platform. My dad got rid of a lot of the wood in 85. Still have enough to make it whalerish.

 

Holy Cow Batman.....look at this site:

http://www.marineconcepts.com/CUB.htm

Someone stole your plans and made it out of fiberglass.

 

Dave,

Those ********, they killed my idea ! ; )

I tried to figure out where the supports and sides were coming from. However, the animation gives me a headache.

You are truly a master of the web search. Must have a good repetoire of + AND and NOT.

My design is to be decidely low tech. No remote controls, actuators. Women in bathing suits are allowed.

They don't show it recessed so I wonder about fishing for bluefin off the back in rolling seas. I thought about trying to recess the front deck, it seemed a little to problematic. Instead a removeable casting/leaning post and/or perimeter rail would give the front deck better non smooth water safety

Certainly some interesting parallels.

 

How about looking at this design as the hull for the project:

The Nina

Don't mean to be a Mertens salesman, but this might allow the back platform and front cabin!

If reds & bluegills liked it, and Florida lakes were, 2 ft deeper I'd be mighty "conflicted"

Dave

 

Dave,

It's interesting that bateau designs are becoming a little less conventional.

I like the hull lines and in fact a lobsterman I know has a boat that is very similar at or below the waterline, though not double wedge.

It also reminds me of a cut down Pearson yacht (of course). I'll be waiting to see how the outboard is placed. I'd like to design something comparable to the Pearson and get a couple hundred grand for them.

Of course it's semi displacement.

Thanks for the head's up more features for consideration.

 

The Nina hull shape is not that of a semi-displacement boat and the quoted speed of 18mph on a 22 foot boat with 30hp is more consistent with a planing hull.

No way could you get a 30hp outboard to fit under that low cover.

Nice looking boat though.

 

Forgive my ignorance but on the Nina: What is a double wedge-type hull?

As to the engine under the cover, I agree with Tom mostly. A short shaft motor might fit but I figure there to be about 32 inches from keel to the top of the motor cover and that won't fit a long shaft motor. Of course the other problem is whether you can raise the motor high enough to get it out of the water.

 

According to:

Down East Lobster Boats

"the double wedge is a sharp bow entry that gradually flattens toward the stern"

Don't bet against Jacques - if he says a 50 will fit - dollars to donut holes - a 50 will fit.

 

Well Dave, That got me to comparing the designs of the NINA and the Sag Harbor 22 .

The NINA specs say:
A classic lobster boat (double wedge type hull);
LOA: 21' 9"; Beam: 6' 11" ; 18 mph with 30 HP
It seems to have hard chines but is called a semi-displacement hull.

The Sag Harbor 22 appears to have a rounded bilge and I would think would ride softer but needs more ower. It's specs are:
LOA: 22'; Beam: 9'; Draft: 15"; Fuel: 100 gal.; Disp: 3300 lbs. ; powered by a single150 HP Yamaha, with a crew of four, and100 gals. of fuel on board, was clocked at 38MPH.

Quite different boats though they have superficially similar designs. On my budget, I could afford to take the NINA out for a day on the water much more frequently than I could the other one.

 

>> Don't bet against Jacques - if he says a 50 will fit -
>> dollars to donut holes - a 50 will fit

I wouldn't dream of betting against either Jacques or Tom.

A 50 long-shaft would fit if you ditched the engine cover or made it taller. It also looks to me like there is 4 feet from the front of the engine cover to the stern - which isn't enough to get a 50hp motor all the way up out of the water in my opinion unless he raised the whole rear end about a foot or made a flap to the rear of the motor well.

So yes, it would fit but not well.

Motor wells look real good but cause a number of problems. Unless the well is very wide it is usually possible to put the cavitation plates and prop under the sides (a bit risky if you hit something). In a shallow drive position (or with a transom jack), you can chop out the sides unless you build in some stops.

 

This is a Handy Billy 21', it will take a 40hp under the hood. Should give you an idea how much height you need.



Very close to Nina.

Gary