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how do I make a bowsprit?

 
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ahoy
Guest





PostPosted: Sun Oct 30, 2005 12:07 pm    Post subject: how do I make a bowsprit? Reply with quote

Hello, I'd like to add a 4' bowsprit to an IP23 sailboat. To what
extent does the bowsprit rely on the rigging for it's strength vs it's
actual strength of materials? I was hoping to use a one inch thick
piece of epai 6 feet long, two feet on deck, four feet for the
bowsprit and 2 more 4' long, one inch thick planks butting the bowstem
all laminated/*** together. About 3 1/2 inches wide with two side
stays and a 5/8" stainless rod for the dolphin catcher and a stay to
the masthead. I'm looking for some advice as to whether this is too
much or too little. Is there a better place to ask this question or
get some information? Thanks for your time.
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Roger Derby
Guest





PostPosted: Sun Oct 30, 2005 2:37 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

Not a simple calculation. Note that the loads go in all directions; up when
at rest, but down when you've buried it in a wave and athwartship when your
jib is pulling on a broad reach.

Do you have a forestay on your mast? Are you going to keep it? If not, how
are you going to transfer the load back to the hull. That forestay is
(arguably) the hardest working line on the boat.

Classically, the heel is buried in heavy timbers, the "partners" (knight
heads) at the bow pick up the side loads, and the gammoning holds it down.
The latter is aided by stays down to the hull. I'd suggest that 1" siding
is too little. You might see if Dave Gerr has anything to say about
bowsprits in his "Nature of Boats."

It's also normal to make provision for unstepping the bowsprit since it gets
damaged easily and the boat fits into storage spaces better without it.
(I'm not sure what you have in mind when you say "all laminated and ***
together.")

Roger
derbyrm@NOSPAMearthlinkNOSPAM.net
http://home.earthlink.net/~derbyrm

"ahoy" <rtefrt@dffasdlf.com> wrote in message
news:8kr8m11glm0hapic3cfjk9vvmm6fjrcvto@4ax.com...
Quote:
Hello, I'd like to add a 4' bowsprit to an IP23 sailboat. To what
extent does the bowsprit rely on the rigging for it's strength vs it's
actual strength of materials? I was hoping to use a one inch thick
piece of epai 6 feet long, two feet on deck, four feet for the
bowsprit and 2 more 4' long, one inch thick planks butting the bowstem
all laminated/*** together. About 3 1/2 inches wide with two side
stays and a 5/8" stainless rod for the dolphin catcher and a stay to
the masthead. I'm looking for some advice as to whether this is too
much or too little. Is there a better place to ask this question or
get some information? Thanks for your time.
Back to top
Jonathan W.
Guest





PostPosted: Sun Oct 30, 2005 4:01 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

I can't speak to bowsprits, but in land based construction the general
rule of thumb for cantilevered decks, bay windows, etc. is 2/3 vs 1/3,
i.e. the exact opposite of what you propose. 2/3 of your structural
member is buried in the existing structure, one third of it is outside,
and free to bear weight. In other words, to have a cantilevered 3 ft
deck/landing, no posts to the ground, you need to your 2x8s buried by 6
feet.

Most timber bowsprits I've seen are as tall/deep as they are thick,
round, or a 4x4, 3x3, etc.....

Why do you want to do this, anyway?



ahoy wrote:

Quote:
Hello, I'd like to add a 4' bowsprit to an IP23 sailboat. To what
extent does the bowsprit rely on the rigging for it's strength vs it's
actual strength of materials? I was hoping to use a one inch thick
piece of epai 6 feet long, two feet on deck, four feet for the
bowsprit and 2 more 4' long, one inch thick planks butting the bowstem
all laminated/*** together. About 3 1/2 inches wide with two side
stays and a 5/8" stainless rod for the dolphin catcher and a stay to
the masthead. I'm looking for some advice as to whether this is too
much or too little. Is there a better place to ask this question or
get some information? Thanks for your time.


--
I am building my daughter an Argie 10 sailing dinghy, check it out:
http://home.comcast.net/~jonsailr
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Dave W
Guest





PostPosted: Sun Oct 30, 2005 6:54 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

Good luck with your plan for the bowsprit. My only comment is that a wire
with a user installed lower fitting is much superior to a rod for the
bobstay. Sooner or later, everyone rams a float or something. A rod will
stay bent; wire goes back to its original straightness all by itself.
Corrosion at the lower end is often a problem because of the cycling in and
out of the water. By using user installed fittings, the cold working of
swaging is avoided and corrosion greatly limited. A great many designs
would benefit from having a bowsprit. It reduces weather helm and is a
perfect place for storing the anchor in the ready position.
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Steve
Guest





PostPosted: Sun Oct 30, 2005 9:12 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

I'm not a purist and recognize that terminology varies with region and
country, however, I could suggest a couple correction in "Bowsprit
Nomenclature" use here.

1. The rod or wire you describe, going from the end of the bowsprit, down to
the stem of the boat is called a "Bobstay" and if you have a strut in the
middle to improve the load geometry, that is called a "Dolphin Striker". The
fitting or attachment where the Bobstay is attached to the stem is call a
"Stem Band".

2. The wires or chains the goes from the end of the bowsprit to the side of
the hull are called "Whisker Stays".

My intentions are not to be 'anal' but to try to preserve the nautical
terminology when ever I have the opportunity. Just constructive
"clarification".


--
My experience and opinion, FWIW
--
Steve
s/v Good Intentions



"ahoy" <rtefrt@dffasdlf.com> wrote in message
news:8kr8m11glm0hapic3cfjk9vvmm6fjrcvto@4ax.com...
Quote:
Hello, I'd like to add a 4' bowsprit to an IP23 sailboat. To what
extent does the bowsprit rely on the rigging for it's strength vs it's
actual strength of materials? I was hoping to use a one inch thick
piece of epai 6 feet long, two feet on deck, four feet for the
bowsprit and 2 more 4' long, one inch thick planks butting the bowstem
all laminated/*** together. About 3 1/2 inches wide with two side
stays and a 5/8" stainless rod for the dolphin catcher and a stay to
the masthead. I'm looking for some advice as to whether this is too
much or too little. Is there a better place to ask this question or
get some information? Thanks for your time.
Back to top
Guest






PostPosted: Mon Oct 31, 2005 7:37 am    Post subject: Re: how do I make a bowsprit? Reply with quote

Take a look at these photos from the Pacific Seacraft Dana 24. Perhaps
similar in size / layout to the IP23...?

Here's the 'sprit + rig:

http://www.pacificseacraft.com/cgi-bin/printview.php?2422

and here's how to buy the 'sprit:

http://www.pacificseacraft.com/parts/notes.php?sc=2473129&cat=bowsprit

Good Luck.

MW
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ahoy
Guest





PostPosted: Mon Oct 31, 2005 1:56 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

On Sun, 30 Oct 2005 09:37:42 GMT, "Roger Derby"
<derbyrm@earthlink.net> wrote:

Quote:
Not a simple calculation. Note that the loads go in all directions; up when
at rest, but down when you've buried it in a wave and athwartship when your
jib is pulling on a broad reach.

Do you have a forestay on your mast? Are you going to keep it? If not, how
are you going to transfer the load back to the hull. That forestay is
(arguably) the hardest working line on the boat.

Yes, I'm going to keep the existing forsail and stay as is so I will
have to figure out how to add another stay to the masthead. There is
also an existing cutter stay mid foredeck. I'm thinking along the
lines of some early Lyle Hess traditional looking boats with a small
yankee cut sail up high on the bowsprit so it clears the pulpit and
bow when whipping about. The rig is down now and decked in the yard
where I can work on it anytime.
Quote:

Classically, the heel is buried in heavy timbers, the "partners" (knight
heads) at the bow pick up the side loads, and the gammoning holds it down.
The latter is aided by stays down to the hull. I'd suggest that 1" siding
is too little. You might see if Dave Gerr has anything to say about
bowsprits in his "Nature of Boats."

Yes, I did notice this when taking my reconasance walk at the local
dock. Unfortunately all the boats I saw were 40'+ heavily built Hans
Christen clones but I do see the tendency to incorperate the heel into
the deck and bow structure. I couldn't find any small boats. One mid
sized wooden boat had a tiny round pine pole which looked like it
could be shipped and seemed to rely on the rigging for it's strength.
Quote:

It's also normal to make provision for unstepping the bowsprit since it gets
damaged easily and the boat fits into storage spaces better without it.
(I'm not sure what you have in mind when you say "all laminated and ***
together.")

The boats I saw looked like super permanant installations. It did

occur to me pitch poling or ramming a piling would wreck the whole
front of the boat and probably bring the mast down unless the
arrangement was mechanically fused somehow or tremendously overbuilt.
Thanks for your response.

Quote:
Roger
derbyrm@NOSPAMearthlinkNOSPAM.net
http://home.earthlink.net/~derbyrm

"ahoy" <rtefrt@dffasdlf.com> wrote in message
news:8kr8m11glm0hapic3cfjk9vvmm6fjrcvto@4ax.com...
Hello, I'd like to add a 4' bowsprit to an IP23 sailboat. To what
extent does the bowsprit rely on the rigging for it's strength vs it's
actual strength of materials? I was hoping to use a one inch thick
piece of epai 6 feet long, two feet on deck, four feet for the
bowsprit and 2 more 4' long, one inch thick planks butting the bowstem
all laminated/*** together. About 3 1/2 inches wide with two side
stays and a 5/8" stainless rod for the dolphin catcher and a stay to
the masthead. I'm looking for some advice as to whether this is too
much or too little. Is there a better place to ask this question or
get some information? Thanks for your time.
Back to top
ahoy
Guest





PostPosted: Mon Oct 31, 2005 2:05 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

On Sun, 30 Oct 2005 06:01:41 -0500, "Jonathan W."
<jonsailr@comcast.net> wrote:

Quote:
I can't speak to bowsprits, but in land based construction the general
rule of thumb for cantilevered decks, bay windows, etc. is 2/3 vs 1/3,
i.e. the exact opposite of what you propose. 2/3 of your structural
member is buried in the existing structure, one third of it is outside,
and free to bear weight. In other words, to have a cantilevered 3 ft
deck/landing, no posts to the ground, you need to your 2x8s buried by 6
feet.

I'm getting the idea the main support is from the rigging forming
various trianges.

Quote:

Most timber bowsprits I've seen are as tall/deep as they are thick,
round, or a 4x4, 3x3, etc.....

Good point. That was my first plan but when I roughed out the pieces
out it felt too heavy and looked disproportionate. I could look for
lighter wood I guess.
Quote:

Why do you want to do this, anyway?

It turns out IP23's are notoriously bad sailors and there is a
commonly perceived need among owners to move the sail effort forward
in an attempt to make the boat come about and perform with any kind of
success upwind. They were offered in various stages of completion and
were not designed specifically as sailboat. Thanks.

Quote:



ahoy wrote:

Hello, I'd like to add a 4' bowsprit to an IP23 sailboat. To what
extent does the bowsprit rely on the rigging for it's strength vs it's
actual strength of materials? I was hoping to use a one inch thick
piece of epai 6 feet long, two feet on deck, four feet for the
bowsprit and 2 more 4' long, one inch thick planks butting the bowstem
all laminated/*** together. About 3 1/2 inches wide with two side
stays and a 5/8" stainless rod for the dolphin catcher and a stay to
the masthead. I'm looking for some advice as to whether this is too
much or too little. Is there a better place to ask this question or
get some information? Thanks for your time.
Back to top
ahoy
Guest





PostPosted: Mon Oct 31, 2005 2:06 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

On Sun, 30 Oct 2005 08:12:42 -0800, "Steve" <estevew@hctc.com> wrote:

Quote:
I'm not a purist and recognize that terminology varies with region and
country, however, I could suggest a couple correction in "Bowsprit
Nomenclature" use here.

1. The rod or wire you describe, going from the end of the bowsprit, down to
the stem of the boat is called a "Bobstay" and if you have a strut in the
middle to improve the load geometry, that is called a "Dolphin Striker". The
fitting or attachment where the Bobstay is attached to the stem is call a
"Stem Band".

2. The wires or chains the goes from the end of the bowsprit to the side of
the hull are called "Whisker Stays".

My intentions are not to be 'anal' but to try to preserve the nautical
terminology when ever I have the opportunity. Just constructive
"clarification".


--
My experience and opinion, FWIW

Nicely put, thank you Steve.
Back to top
Denis Marier
Guest





PostPosted: Mon Oct 31, 2005 6:01 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

Thanks for the right terminology. Can the same terminology be used for a
sternsprit.
I do not no much about bowsprits. I have seeing some made with wood and
other with 2 " pipe.
I often wonder what are the advantages and drawback of having a bowsprit.

"ahoy" <rtefrt@dffasdlf.com> wrote in message
news:7pnbm19eoq6sgajg6ugsiknt34rpm67nkt@4ax.com...
Quote:
On Sun, 30 Oct 2005 08:12:42 -0800, "Steve" <estevew@hctc.com> wrote:

I'm not a purist and recognize that terminology varies with region and
country, however, I could suggest a couple correction in "Bowsprit
Nomenclature" use here.

1. The rod or wire you describe, going from the end of the bowsprit, down
to
the stem of the boat is called a "Bobstay" and if you have a strut in the
middle to improve the load geometry, that is called a "Dolphin Striker".
The
fitting or attachment where the Bobstay is attached to the stem is call a
"Stem Band".

2. The wires or chains the goes from the end of the bowsprit to the side
of
the hull are called "Whisker Stays".

My intentions are not to be 'anal' but to try to preserve the nautical
terminology when ever I have the opportunity. Just constructive
"clarification".


--
My experience and opinion, FWIW

Nicely put, thank you Steve.
Back to top
Dave W
Guest





PostPosted: Mon Oct 31, 2005 7:57 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

A "bowsprit on the stern" is called a boomkin. Usually, they are wishbone
shaped when viewed from the top; two members that meet.
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Steve
Guest





PostPosted: Mon Oct 31, 2005 8:43 pm    Post subject: Re: how do I make a bowsprit? Reply with quote

I have had bowsprits on most of my dozen sailboats over the past 45yrs on
the water. The main advantage is increasing the overall length, with respect
to carrying more sail or more head sail combinations.

I don't like to see it as a advantage for getting the anchor off the bow. I
much prefer to have my anchor roller at the stem head since a roller on the
end of the bowsprit puts too much load on the headstay and much too much
noise when the boat is hobby horsing at anchor.

Here are a couple of pictures of my present arrangement that allows me to
have two bow anchors, on chain, lead to a single anchor windlass.

http://www.hctc.com/~esteve/INGRID%20PICs/dogonbw1.jpg

http://www.hctc.com/~esteve/INGRID%20PICs/dogonbow.jpg

(the dog "Shipmate" is no longer part of the crew)

The bowsprit is made of 2" SS pipe with aluminum deck plating. There are cut
outs for the anchors to come thru. I'm very happy with the whole system.

Note that this type of bowsprit/platform eliminates the need for Whisker
Stays.

The Bob Stay (not pictured) is 5/8" rod. I've run into the dock and a buoy,
at slow speed and it hasn't bent (yet). The stem band is 3/4" X 1 1/4" X 4'
and runs down the stem and is through bolted with a similar backing plate at
each bolt.

--
My experience and opinion, FWIW

--
Steve
s/v Good Intentions


"Denis Marier" <marierdj@nb.sympatico.ca> wrote in message
news:XAo9f.116759$Ph4.3584162@ursa-nb00s0.nbnet.nb.ca...
Quote:
I do not no much about bowsprits. I have seeing some made with wood and
other with 2 " pipe.
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