Some questions

[BHOFM]

Everyone here knows I am building a boat..

I have a couple of questions..

I have a lot of pieces of aluminum, strips, 1/8" and 1/4"
1" and 2" wide several feet long.

Is there any reason I can not make chain plates and tangs
for the mast head from this material?

It is hardened aircraft stock, don;t know the alloy number.

The plans call for brass, 1/8"X3/4" for all the parts.

Next question,, It looks like I may have built the boat
about half design weight. Using cedar instead of oak.
I picked it up off the jig and it is very light, should be
about 300lbs, and it is not even close to that!

The seats are not in it yet, but it still has the mold
frames.

Any thoughts about this???

[TeddyDiver]

Replacing brass with aluminium doesn't change your weight issue. Maybe installing one BHFOM onboard brings a balance (to the Force):D

[PAR]

You substitution is a classic example of what not to do. Cedar is considerably lighter then oak, as you've noted, but it's also considerably weaker too. So now, you have a light weight weakling, congratulations and don't venture farther from shore then you can swim back to.

Now that's it's lighter, it'll have to be ballasted down to her lines, which will place exponentially increasing strains on her rig and structural elements.

Aluminum is a lousy metal for "hard points" in the rig. It doesn't like to "work" and it's easily deformed. You need a "prouder" metal.

When making substitution for any thing, you should make a change to a material with similar physical properties or calculate the relative strength necessary and change the dimensions of the weaker (or stronger) substitute. A cedar 2 x 4 is the weak kneed, redheaded step child of an oak 2 x 4. Changing one out for the other is just pure folly. Have your family update the insurance policies.

[rwatson]

Maybe all is not lost - the talk of "seats not in it" and "picking it up" leads me to think why the hell a boat that small was specified in oak in the first place. Maybe some epoxy and FG will solve all.

Tell us more about the boat BF. Maybe its a sailing canoe with a sail so small that you could use a rubber band.

And yes, Aluminium would be a really bad metal to use for something in tension like mast rigging, but if Brass is the "approved" option, its not much better.

Is this the one at
http://www.boatdesign.net/forums/showthread.php?t=24009 ??

If so, oak was a bad idea anyway. Who "designed" this boat???

[dsuursoo]

i'm gonna feel bad, but i have to take Par's side here. wear flotation. cedar smells nice, works easily, and is light, and that's about the only advantages over oak. if i ever want light weight AND high strength, i use sitka spruce. if i want high strength, i use white oak. all i'd use cedar for in a boat is maybe decorative bits in the interior, and even then...

aluminum... the heat generated by machining and welding can easily weaken it to the point where you don't want to trust it. get it heat treated afterwards though, and hey!

course, that's wicked expensive. and welding aluminum is not easy.

you might want to save yourself the trouble...

not trying to be a downer.

[BHOFM]

The thing is, I am on a budget and I had the cedar. Around
here, you can't buy any thing but "lumber"!

Any thing that is nice, is individually wrapped and so over
priced the boat would have cost thousands of dollars to
build! The 1"X12"X12' cedar I have is over $40 per board.
It is cut under size on the width and I got it for $7 each!

I did not feel good about the aluminum to start with. And
it seems My feeling were right!

We do not have a supply of brass or stainless in this area,
I have done a lot of looking.

Does anyone know of a marine hardware supplier that is
reasonable?

Duckworks has some of the things I need and they seem
to be priced right.

A lot of you are located on the coasts and there is a lot
of boat construction and interest in your area. Here I am
the crazy old man down the street building a wooden
boat. I could have done it in our airplane hanger, but it
is 10 miles away, I choose to do it in the driveway so I
could work a little at a time and not have to move all
my wood working equipment, and the weather has not
been a friend the last few days.

I am not able to work for extended times, I have to take
a lot of breaks, so I get a lot more done here than I would
at the hanger.

Also, it is just me and the wife and we are both strong
swimmers. And I always have life jackets and cushions
on board.

The lake where we will be going is long, 70+ miles but
not very wide, only a few spots where it is over a mile
wide. The biggest thing we will ever see a a wake from
a house boat.

Thanks for taking time to comment and read the babblings
of a cranky old man.

Par could probably build this boat in a weekend with a
Swiss Army knife and his Boy Scout axe! Fell the trees
and twist his own rope.
:P :P :P

[rwatson]

So is it the boat on the link or not???

If it is, and you planked it with 1" planks, you aint got nuthin to worry about except weatherproofing it.

[dsuursoo]

inch thick cedar you say?

should float alright, but you'll most likely need extra ballast. be careful.

and if the wind gets frisky, head in.

westmarine is good for me. dunno about your area.

[BHOFM]

So is it the boat on the link or not???

If it is, and you planked it with 1" planks, you aint got nuthin to worry about except weatherproofing it.

Yes, that's my project.

The frame, such as it is, is 1" cedar, the skin is 1/4" ply
on the sides and 3/8" on the bottom. The seats with knees
are the actual internal frames. I added some stiffeners on
the sides and bottom. It has side seats as well so the center
is a square. There are braces under the center of the seats
as well. I made the transom thicker and made the stem
more robust as well.

You can see in the picture, I am going to make the side
seats go back to fill in between the seats and enlarge
the breast hook, transom knees and mast bench some.

If the sides are not stiff enough I may add a inside
combing.

One thing I think helps is the bottom does not have a
center seam. one sheet covered it side to side with
a 3' piece in the front.

The boat is for light day sailing only. If there is a chance
of any weather, we will stay at home. I am going to fit
oar locks so we can just go fishing now and then.

westmarine is good for me. dunno about your area.

I have dealt with West in the past, but can not find any
small hardware on their web site.


Sorry for going on and on.

Edit,, I did some searching at Duckworks and found everything
I need and it is very reasonable..

The Chain plates to West were $50 each, DW's are $4.

[rwatson]

End of concern

The WRC ribs will be just as good as Oak if the waterproofing is done right. If you are only using plywood skin, then all the fal-de-ral about dangerous boating and ballast is not applicable.

For a 12 ft boat, the plates and tangs wont have to be huge either.

[dsuursoo]

yeah, given the build techniques, you should be good to go.

good job on duckworks. me, i've always liked using wood for points where standing rigging sets, deadeyes and all. it looks so wonderfully old-timey.

but i'm odd like that.

squaresails on a trimaran. what was i thinking?

[BHOFM]

For any one that does not check my build thread, the hull
is done and turned over, we weighed it, with the frames
still in and no seats, the painted hull weighs 106lbs, I
need two hundred pounds of rigging!

[rwatson]

You do *not* need 200 pounds of rigging!!!!!

If you think you need ballast, stick some lead or bricks or plastic containers with water in the hull.

Your freewebs web site has nothing about the boat in it. Its a bit hard to track the boat pictures down.

[Ozducati]

Good on ya BHOFM for having a go and using available materials!!!
I did the same thing a few years ago and built an 8 foot sailing dinghy from 1/10" rigid plastic sheet. It only weighed 50lbs and stability was not an issue.
I can't see a problem with using the 6mm thick ally for making the chainplates.... they make whole boats out thinner gauge ally and they seem to survive ok.
Cartons of beer make good ballast.
Well done! You've put in the effort & I hope you enjoy the fruits of your work.

[dsuursoo]

yeah, 6mm aluminimuminum should be good. try for something like 6061, one of the aircraft grades. best strength for the weight, in my opinion. tough to bend it without breaking it, so if you need something that wraps around a corner, either get an angle section or get it welded.

but you know, i could see using some kind of sonic weld to make a boat completely out of really heavy plastic. you know, the sort of stuff they make those big drums out of.

[Ozducati]

G'day Dsuursoo,
Plastic boats?..... check this out ---> http://www.duckworksmagazine.com/07/designs/plastic/index.htm