[bolger] Re: Windsprint Hull Fairness
I built and currently sail a Windsprint. I used 1/2" plywood on the bottom
and I think it makes for a sturdier boat. I butted the plywood and then
scribed it. I used an electric planer to fair the edges. Not sure about
getting everything centered. My center lines matched up and the hull looked
straight to me. I added decking fore, aft and sides. I'm constantly messing
with the rig. I also think staring at the boat is good work!
Mike Masten
In a message dated 10/25/99 6:08:41 AM,rlundy@...writes:
<< Windsprint does not have an expanded bottom drawing. The builder is
expected to true the hull and then scribe the bottom to fit. Now that
I know I can shim out the unfair spot, I need a way to check the hull
for square. I'm not sure just lining up the marked centerlines (going
to go back and check that all these are REALLY centered anyway) and
pulling a string along them to line everything up will really make
everything square and true. Help?
and I think it makes for a sturdier boat. I butted the plywood and then
scribed it. I used an electric planer to fair the edges. Not sure about
getting everything centered. My center lines matched up and the hull looked
straight to me. I added decking fore, aft and sides. I'm constantly messing
with the rig. I also think staring at the boat is good work!
Mike Masten
In a message dated 10/25/99 6:08:41 AM,rlundy@...writes:
<< Windsprint does not have an expanded bottom drawing. The builder is
expected to true the hull and then scribe the bottom to fit. Now that
I know I can shim out the unfair spot, I need a way to check the hull
for square. I'm not sure just lining up the marked centerlines (going
to go back and check that all these are REALLY centered anyway) and
pulling a string along them to line everything up will really make
everything square and true. Help?
>>
Had to go by the house at lunch today. Found 15 minutes to take some
measurements.
At each mold station the height off the floor was the same. So no twist
as far as I can see. Measuring the bottom of the molds turned up some
"off by 1/16" either way. Had to move one centerline over by 1/16".
Nothing major till I came to the forward mold (where the unfair spot
is). I'm somehow short by 3/16ths on the bottom of this mold. Now,
the port side lies fair as can be. The starboard side is where the
ugly spot is. I played with the sheetrock screws, upper and lower for
a few minutes and did the same on the other side. At one point, I
backed the screw out of the chine edge completely to see where this
this would lead. Interestingly, it still wouldn't lay in a fair curve.
Further examination showed, as I stated before, a "hard" spot right
beside the butt block. So... I think I had a combination of a hard
spot in the plywood and a too little bottom width on that mold. I feel
OK about this diagnosis since laying a batten along the gunwale edge
showed it laying in a beatiful curve. To correct I've backed off both
the port and starboard chine edge fastenings enought that most of the
flat spot is gone and shimmed appropriately with tongue depressors.
Measuring outward from the mold centerline keeps everything
symmetrical. You really can only see it now when you look down at the
knife edge of the plywood. The hull side looks fair. After the chine
log goes on, it should be almost invisible, at least until I put gloss
paint on the boat. All pictures taken will be of the port side only.
Hope I didn't take up too much of everyone's time with this. All of us
want to avoid the "horrible twist". I'm chalking this up to the weird
twisted shapes you get in B/C pine plywood and a little bad luck. And
I learned alot about checking a hull for square.
Robert Lundy
St. Petersburg, Fla.
ghc <ghart-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=563
measurements.
At each mold station the height off the floor was the same. So no twist
as far as I can see. Measuring the bottom of the molds turned up some
"off by 1/16" either way. Had to move one centerline over by 1/16".
Nothing major till I came to the forward mold (where the unfair spot
is). I'm somehow short by 3/16ths on the bottom of this mold. Now,
the port side lies fair as can be. The starboard side is where the
ugly spot is. I played with the sheetrock screws, upper and lower for
a few minutes and did the same on the other side. At one point, I
backed the screw out of the chine edge completely to see where this
this would lead. Interestingly, it still wouldn't lay in a fair curve.
Further examination showed, as I stated before, a "hard" spot right
beside the butt block. So... I think I had a combination of a hard
spot in the plywood and a too little bottom width on that mold. I feel
OK about this diagnosis since laying a batten along the gunwale edge
showed it laying in a beatiful curve. To correct I've backed off both
the port and starboard chine edge fastenings enought that most of the
flat spot is gone and shimmed appropriately with tongue depressors.
Measuring outward from the mold centerline keeps everything
symmetrical. You really can only see it now when you look down at the
knife edge of the plywood. The hull side looks fair. After the chine
log goes on, it should be almost invisible, at least until I put gloss
paint on the boat. All pictures taken will be of the port side only.
Hope I didn't take up too much of everyone's time with this. All of us
want to avoid the "horrible twist". I'm chalking this up to the weird
twisted shapes you get in B/C pine plywood and a little bad luck. And
I learned alot about checking a hull for square.
Robert Lundy
St. Petersburg, Fla.
ghc <ghart-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=563
> Matching the diagonals of a rectangle will make it square. You cando the
> same thing between any pair of bulkheads.check
>
> Or, you can arrange a string line down the center of your hull and
> the center of each bulkhead. If you find one you don't like, you canpull
> it straight by nailing a temporary strip of lumber on a diagonal.to
>
> To check for twist, you can measure "3-d" diagonals, but it's simpler
> put your hull on the floor and measure up to each side of eachbulkhead.
>hull
> Gregg
>
>
> At 10:53 AM 10/25/1999 EDT, you wrote:
> >>Now that
> >>I know I can shim out the unfair spot, I need a way to check the
> >>for square. I'm not sure just lining up the marked centerlines(going
> >>to go back and check that all these are REALLY centered anyway) andhearing
> >>pulling a string along them to line everything up will really make
> >>everything square and true. Help?>
> >
> >Robert and Amy;
> > My chief dread is the possibility of building a boat that is
> >asymmetrical, one that has a "twist" built in. I vaguely remember
> >about a technique that is something like running two tight stringsfrom near
> >the bow to the stern that crossover somewhere in the middle. Thenasymmetry
> >could be judged by making measurements from the crossover point ofthe
> >strings to the attachment points. I don't know exactly how thisworks, but
> >someone posted an e-mail on it recently but I have been unable tofind the
> >post. Perhaps someone who knows more about the technique couldpost? I
> >would find it quite helpful. (I imagine you could also varyattachment
> points
> >on the chine vs gunwale dimension) Regards, Warren
> >
Matching the diagonals of a rectangle will make it square. You can do the
same thing between any pair of bulkheads.
Or, you can arrange a string line down the center of your hull and check
the center of each bulkhead. If you find one you don't like, you can pull
it straight by nailing a temporary strip of lumber on a diagonal.
To check for twist, you can measure "3-d" diagonals, but it's simpler to
put your hull on the floor and measure up to each side of each bulkhead.
Gregg
At 10:53 AM 10/25/1999 EDT, you wrote:
same thing between any pair of bulkheads.
Or, you can arrange a string line down the center of your hull and check
the center of each bulkhead. If you find one you don't like, you can pull
it straight by nailing a temporary strip of lumber on a diagonal.
To check for twist, you can measure "3-d" diagonals, but it's simpler to
put your hull on the floor and measure up to each side of each bulkhead.
Gregg
At 10:53 AM 10/25/1999 EDT, you wrote:
>>Now thatpoints
>>I know I can shim out the unfair spot, I need a way to check the hull
>>for square. I'm not sure just lining up the marked centerlines (going
>>to go back and check that all these are REALLY centered anyway) and
>>pulling a string along them to line everything up will really make
>>everything square and true. Help?>
>
>Robert and Amy;
> My chief dread is the possibility of building a boat that is
>asymmetrical, one that has a "twist" built in. I vaguely remember hearing
>about a technique that is something like running two tight strings from near
>the bow to the stern that crossover somewhere in the middle. Then asymmetry
>could be judged by making measurements from the crossover point of the
>strings to the attachment points. I don't know exactly how this works, but
>someone posted an e-mail on it recently but I have been unable to find the
>post. Perhaps someone who knows more about the technique could post? I
>would find it quite helpful. (I imagine you could also vary attachment
>on the chine vs gunwale dimension) Regards, Warren
>
>------------------------------------------------------------------------
>
>eGroups.com home:http://www.egroups.com/group/bolger
>http://www.egroups.com- Simplifying group communications
>
>
>
>
>
>Now thatRobert and Amy;
>I know I can shim out the unfair spot, I need a way to check the hull
>for square. I'm not sure just lining up the marked centerlines (going
>to go back and check that all these are REALLY centered anyway) and
>pulling a string along them to line everything up will really make
>everything square and true. Help?>
My chief dread is the possibility of building a boat that is
asymmetrical, one that has a "twist" built in. I vaguely remember hearing
about a technique that is something like running two tight strings from near
the bow to the stern that crossover somewhere in the middle. Then asymmetry
could be judged by making measurements from the crossover point of the
strings to the attachment points. I don't know exactly how this works, but
someone posted an e-mail on it recently but I have been unable to find the
post. Perhaps someone who knows more about the technique could post? I
would find it quite helpful. (I imagine you could also vary attachment points
on the chine vs gunwale dimension) Regards, Warren
Hey, thanks for the good comments. After I posted the update, I went
back into the garage and did some more staring (staring at your work is
underrated as a tool). After long contemplation, I took my cordless
drill and backed off the sheetrock screw holding the chine edge of the
forward temporary mold by a bit less than 1/4 inch. Presto, the unfair
spot is gone. Remember, the Gunwale edge seemed fair. I'm starting to
wonder if I didn't make a small cutting error in the forward mold.
Remember, Windsprint has NO permanent molds/frames. I figure I can
shim all I want as everything I've read says make sure all the curves
lay fair.
Windsprint does not have an expanded bottom drawing. The builder is
expected to true the hull and then scribe the bottom to fit. Now that
I know I can shim out the unfair spot, I need a way to check the hull
for square. I'm not sure just lining up the marked centerlines (going
to go back and check that all these are REALLY centered anyway) and
pulling a string along them to line everything up will really make
everything square and true. Help?
Robert & Amy Lundy
St. Petersburg, Fla.
back into the garage and did some more staring (staring at your work is
underrated as a tool). After long contemplation, I took my cordless
drill and backed off the sheetrock screw holding the chine edge of the
forward temporary mold by a bit less than 1/4 inch. Presto, the unfair
spot is gone. Remember, the Gunwale edge seemed fair. I'm starting to
wonder if I didn't make a small cutting error in the forward mold.
Remember, Windsprint has NO permanent molds/frames. I figure I can
shim all I want as everything I've read says make sure all the curves
lay fair.
Windsprint does not have an expanded bottom drawing. The builder is
expected to true the hull and then scribe the bottom to fit. Now that
I know I can shim out the unfair spot, I need a way to check the hull
for square. I'm not sure just lining up the marked centerlines (going
to go back and check that all these are REALLY centered anyway) and
pulling a string along them to line everything up will really make
everything square and true. Help?
Robert & Amy Lundy
St. Petersburg, Fla.