Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Morgan Ohlson
 
Posts: n/a
Default Perfect cruising bermuda dinghy

Perfect cruising bermuda dinghy

I put this as what I believe best for a 18' cruising dinghy, main 10,5m2
(unstayed mast)... which is probably wrong, but maybe not all.! ;o)

# Loose foot
# Full battens
# 2 reefing lines (which type?)
# Boltrope
# Foot slightly raising (5-15deg)
# Telltales
# Crosscut Polyester (weight?)
# Does weave manufacturer matter?

# Jib around 35% of SA (reasonable big, reasonable reef step)
# Same weave?

Anything else that cannot be missing on a modern (?) dinghy rig?
Further hints?


Morgan O.
  #2   Report Post  
William R. Watt
 
Posts: n/a
Default


Morgan Ohlson ) writes:

Anything else that cannot be missing on a modern (?) dinghy rig?


some things to consider.....

preventer? (eg., boom vang)

how would the main be sheeted?
center sheeting or transom?
would it need a traveller?

all the jibs I've seen have had adjustable fairleads.
some way of tensioning the jib luff so it doesn't sag.

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned
  #3   Report Post  
Morgan Ohlson
 
Posts: n/a
Default

On 23 Oct 2004 21:30:00 GMT, William R. Watt wrote:

Morgan Ohlson ) writes:

Anything else that cannot be missing on a modern (?) dinghy rig?


some things to consider.....

preventer? (eg., boom vang)

how would the main be sheeted?
center sheeting or transom?
would it need a traveller?

all the jibs I've seen have had adjustable fairleads.
some way of tensioning the jib luff so it doesn't sag.


Is the vang mounted further out on the boom if transom sheeting is used?

What about kick rod?

Center or transom sheeting is what I'm just conserning my brain with. It
looks as there can be a problem to fit in a center traveler properly without
a bulkhead to build it on.
....but on the other hand that bulkhead may be needed.

Isn't a traveller allways good to have to gain rig controll?

Morgan O.
  #4   Report Post  
Stephen Baker
 
Posts: n/a
Default

Morgan says:

Center or transom sheeting is what I'm just conserning my brain with.


If you have a loose-footed main, then I would seriously recommend end-boom
(transom) sheeting, or the bending moments in the boom will be extremely high.

Steve
  #5   Report Post  
William R. Watt
 
Posts: n/a
Default


Stephen Baker ) writes:
Morgan says:

Center or transom sheeting is what I'm just conserning my brain with.


If you have a loose-footed main, then I would seriously recommend end-boom
(transom) sheeting, or the bending moments in the boom will be extremely high.


you can run the sheet from the boom end to a block in the middle of the
boom. that keeps it up out of the way and drops it pretty well into a
block mounted, say, on the rear of the centreboard trunk. with a 70 sq ft
main sail you'll need the leverage (mechanical advantage) of a multi part
mainsheet fed through blocks. if you are going to be cruising small lakes
and rivers with shifty winds you won't be able to cleat the mainsheet.
you'll have to hold it in your hand all the time. you probably won't cleat
the mainsheet on an 18 ft dingy anyway. too light and responsive. a rachet
block is quite common and would take some strain off the arm holding the
mainsheet. something to consider later if you find the strain on the arm
too uncomfortable.

the centreboard has to be top braced against lateral (sideway) stresses,
sometimes done with a seat, sometimes with a simple thwart, on which a
traveller and compass can be mounted. I seem to recall the back end of dingy
centreboard trunks being braced by a metal mainsheet traveller alone. the
traveller mostly just helps keep the sail flat when close hauled but also
helps as a preventer. it's not essential for dingy cruising. you can see
these things on photos and diagrams of sailing dingys like the Wayfarer.
I don't know if there are any formulae covering these things, except of
course for the mechanical advantage of the main sheet blocks. It's mostly
trial and error and tales told by old dingy racers.

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned


  #6   Report Post  
Morgan Ohlson
 
Posts: n/a
Default

On 24 Oct 2004 14:06:56 GMT, William R. Watt wrote:

Stephen Baker ) writes:
Morgan says:

Center or transom sheeting is what I'm just conserning my brain with.


If you have a loose-footed main, then I would seriously recommend end-boom
(transom) sheeting, or the bending moments in the boom will be extremely high.


you can run the sheet from the boom end to a block in the middle of the
boom. that keeps it up out of the way and drops it pretty well into a
block mounted, say, on the rear of the centreboard trunk. with a 70 sq ft
main sail you'll need the leverage (mechanical advantage) of a multi part
mainsheet fed through blocks. if you are going to be cruising small lakes
and rivers with shifty winds you won't be able to cleat the mainsheet.
you'll have to hold it in your hand all the time. you probably won't cleat
the mainsheet on an 18 ft dingy anyway. too light and responsive. a rachet
block is quite common and would take some strain off the arm holding the
mainsheet. something to consider later if you find the strain on the arm
too uncomfortable.

the centreboard has to be top braced against lateral (sideway) stresses,
sometimes done with a seat, sometimes with a simple thwart, on which a
traveller and compass can be mounted. I seem to recall the back end of dingy
centreboard trunks being braced by a metal mainsheet traveller alone. the
traveller mostly just helps keep the sail flat when close hauled but also
helps as a preventer. it's not essential for dingy cruising. you can see
these things on photos and diagrams of sailing dingys like the Wayfarer.
I don't know if there are any formulae covering these things, except of
course for the mechanical advantage of the main sheet blocks. It's mostly
trial and error and tales told by old dingy racers.



It's quite common with slightly bent travelers (low at ends)... more seldom
straight. (correct?). What is the main benefit?

To get a transom sheeting an extended boom may be necessary. Does that have
any complications in other ways?

Morgan O.
  #7   Report Post  
Ian Malcolm
 
Posts: n/a
Default

Morgan Ohlson wrote:
On 24 Oct 2004 14:06:56 GMT, William R. Watt wrote:


Stephen Baker ) writes:

Morgan says:


Center or transom sheeting is what I'm just conserning my brain with.

If you have a loose-footed main, then I would seriously recommend end-boom
(transom) sheeting, or the bending moments in the boom will be extremely high.


you can run the sheet from the boom end to a block in the middle of the
boom. that keeps it up out of the way and drops it pretty well into a
block mounted, say, on the rear of the centreboard trunk. with a 70 sq ft
main sail you'll need the leverage (mechanical advantage) of a multi part
mainsheet fed through blocks. if you are going to be cruising small lakes
and rivers with shifty winds you won't be able to cleat the mainsheet.
you'll have to hold it in your hand all the time. you probably won't cleat
the mainsheet on an 18 ft dingy anyway. too light and responsive. a rachet
block is quite common and would take some strain off the arm holding the
mainsheet. something to consider later if you find the strain on the arm
too uncomfortable.

the centreboard has to be top braced against lateral (sideway) stresses,
sometimes done with a seat, sometimes with a simple thwart, on which a
traveller and compass can be mounted. I seem to recall the back end of dingy
centreboard trunks being braced by a metal mainsheet traveller alone. the
traveller mostly just helps keep the sail flat when close hauled but also
helps as a preventer. it's not essential for dingy cruising. you can see
these things on photos and diagrams of sailing dingys like the Wayfarer.
I don't know if there are any formulae covering these things, except of
course for the mechanical advantage of the main sheet blocks. It's mostly
trial and error and tales told by old dingy racers.




It's quite common with slightly bent travelers (low at ends)... more seldom
straight. (correct?). What is the main benefit?

To get a transom sheeting an extended boom may be necessary. Does that have
any complications in other ways?


I have seen no end of trouble with boom end sheeting on dinghies. The
usual problems include the common pin and swivelling strap boom end
fitting failing in heavy weather, the multi part mainsheet wrapping
round itself when gybing so you cant let the sail out without hauling
it right in to clear the jam, and the mainsheet catching on the rudder
stock or the corner of the transom when gybing causing all sorts of
grief :-(. For a crusing dinghy, it will also make it unsafe to keep an
outboard on the transom.

I strongly reccomend reconsidering the boom end sheeting. If you go to
centre sheeting, you will also need the foot of the sail attached to the
boom which is no problem with a bolt rope on it.

Have eyelets fitted in the foot of the sail just above the boom 2" aft
of vertically in line with the reefing clew eyes on the leech so the
sail doesnt get worn through by being trapped against the boom by the
reefing lines. Each reefing line should be tied off using a bowline
round the boom through the eyelet, leaving just enough slack to not
affect the set of the sail when you arent reefed and led up through the
appropriate reef eye in the leech and down to the end of the boom and
then to whatever system you use for cleating the reefing lines. Although
the eyelets just above the boom wouldnt be needed if your reefing lines
were secured to the side or bottom of the boom like on a yacht, that
would put a massive twisting load on the gooseneck, which dinghy
goosenecks are NOT designed to withstand.

Dont bother with single line reefing, a spring gate hook at the
gooseneck on the same pin as is used for the Tack eye is much better
than the extra friction and complexity of having shuttle blocks inside
the boom. I have thin bungee threaded from the luff to the leech and
back again through all the cringles for each reef with small plastic
hooks on one side of the sail so I dont have to bother with tying
reefing points, they just hook together under the boom round the hanging
'bag' of sail. The bungee should be just slack with the sail streched
tight along that line of cringles before you hook it round the boom.
Also if you forget one when shaking out a reef, there is enough stretch
in the bungee to save the sail from being ripped.

The only difficulty I have with the system is that the luff has a
boltrope that slides into the mast groove so I have a lot of loose sail
+ the boom to control when lowering it. For a cruising dinghy 15' I'd
strongly reccomend having slides up the luff retained by a pin or a gate
at the bottom of the groove and a topping lift or better yet lazyjacks
so the sail can be dropped quickly under full control without bashing
the helm on the head with the boom or loosing the crew under the heap of
sail.

An unstayed rig with a jib is going to be a lot more trouble than having
shrouds as the mast will need to be a heavier section and there will be
a lot of stress on the partners and step. You will also have a LOT more
trouble getting satisfactory jib luff tension. Avoid highfield levers
for the jib halyard tensioner, IMHO they are the invention of the devil.
I have a tensioner setup that uses a 2:1 tackle that sweats the halyard
sideways before the cleat. Looking at the angles I reckon its worth a
4:1 or 5:1 advantage pulling on the halyard. You may not be able to use
this setup, but if I had to use a different setup I'd rather have a
muscle box that can be released in a controlled fashion (even though
they are very inefficient) thatn a highfield lever which will do its
bset to take your fingers off if you are tired or careless when you let
it off. Figure on carrying a minimum of two jibs if you are not having
roller reefing as you will want to keep the rig balanced with one reef
in to avoid excessive weather helm. N.B. most small jib roller gears are
only designed for furling ie. 100% out or 0% out and will break if used
for reefing eg. 50% out in strong winds. The roller reefing gears are
quite a bit more expensive, so I decided NOT to get one.

On the subject of travellers and sheeting etc. The total sail area of my
Albacore is ~125 sq feet (11.65 sq m) and she's 15' LOA and LWL which
would be pretty close to the LWL of an 18 footer that doesn't have a
vertical stem so the loads are closely comparable to your proposed
design. The beam is 5'6" which would be less than you'd want for an 18'
cruising dinghy and my traveller horse is unsupported 1.5" aluminium
alloy tube running right across the full beam. Three parts of the four
part center mainsheet lead to the traveller car, the fourth part runs to
a swivel block with a cleat (which does get used quite a bit, mostly to
rest my hand) on the back of the centerboard capping about 6" behind
the traveller. The mainsheet leads through two single blocks on the
boom, one over the traveller, the other over the swivel block. This
spreads the load on the boom. When gybing I grab two parts of the
mainsheet and control the boom as it comes over (keep your elbow bent
:-) ). The traveller control line is a 3:1 continuous loop with turning
blocks and cleats on the centreboard cap so I get a streight pull on it
when I want to use it when sitting out. The original system was 2:1
cleating under the gunwales which was pretty useless in a blow. The
traveler horse bends up about 3" in the middle if close hauled in a
force 5 with two people hiking. Its been doing that for the past 40
years without any problems. I reckon you'd be fine with a modern X
section track bolted to an alloy tube to stiffen it for a span of about
6 feet. No bulkhead required. Remember a 6' long track at mid boom is
equivalent to one 12' long :-) at the transom. With centre boom
sheeting and a traveller you dont need quite as powerfull a kicking
strap (boom vang). If you stick to boom end sheeting you will need
about 16:1 to get the leech flat enough off the wind in a blow. This
will mean you will need either a massive boom section or to internally
sleave it for the forward third of its length to stop it buckling. You
will also have problems with the amount of mast bend it induces pulling
all the shape out of the luff of the sail. I find 4:1 works well for me
with centre sheeting and a full width traveller.

Finally I hope you are fitting a pivoting centreboard not a daggerboard
as the ability to fine tune the CLR to match the CE when reefed and
reduce the weather helm if using main only is worth all the added
complexity alone and if you touch bottom with it at speed you will be
glad it can kick up rather than snapping off or ripping the trunk out of
the hull with you miles from where you launched.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
[dot]=.
*Warning* SPAM TRAP set in header, Use email address in sig. if you must.
'Stingo' Albacore #1554 - 15' Uffa Fox designed, All varnished hot
moulded wooden racing dinghy circa. 1961

  #8   Report Post  
William R. Watt
 
Posts: n/a
Default


Ian Malcolm ) writes:


Albacore details

As someone who has also raced Albacores it was not only nice to read so
much familiar detail but to recall the thrill of hiking out while keeping
the boat planing in a stiff breeze. I knew a fellow who went on a short
inland camping and cruising voyage in his Albacore. There was a photo of
him sitting in a folding canvas "deck" chair perched precariously on the
deck.

However I doubt a cruising dingy needs to be as intricately rigged as a
racing dingy unless the crusing dingy has a planing hull, and that would
be a racing/crusing dingy like the Wayfarer. In "Dinghies for all Waters",
Eric Coleman strongly recommends a heavier, high freeboard, dingy for
crusing as a light responsive boat is too lively for relaxed crusing. He
prefered converted small fishing boats for cruising to racing boats. I
belive his Roamer design was well accepted among British dingy cruising
sailors. I've seen a photo of one on the Internet.

Reading about the Albacore I realized I had forgot a useful feature of a
jib is the ability to drift with the sails hove to while eating, etc. I've
done that between heats at regattas, and for jumping overboard to cool
off.

While I'm on this topic I'd like to suggest for the home builder an
inexpensive wooden boom with an X cross section, a design pioneered by TF
Jones and described in his book "New Plywood Boats". He's had one on his
catamaran for some time. He describes inexpensive home made hardware for
the boom as well. I don't think his boom is made of plywood but I would
think it possible.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
[dot]=.
*Warning* SPAM TRAP set in header, Use email address in sig. if you must.
'Stingo' Albacore #1554 - 15' Uffa Fox designed, All varnished hot
moulded wooden racing dinghy circa. 1961


There was a hot mouled plywood Albacore here in Ottawa, unique and very
attractive boat. The layers of plywood strips are laid 45 deg or so to the
waterline and 90 deg or so to each other. Light, strong, long lasting
construction.


--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned
  #10   Report Post  
Ian Malcolm
 
Posts: n/a
Default

William R. Watt wrote:
Ian Malcolm ) writes:


Albacore details

I primarily wrote what I did because the OP's intended sail area was
comparable to the Albacore with a slightly larger hull and I thought he
might be making a mistake to go for end boom sheeted loose footed
unstayed BERMUDAN rig.

As someone who has also raced Albacores it was not only nice to read so
much familiar detail but to recall the thrill of hiking out while keeping
the boat planing in a stiff breeze. I knew a fellow who went on a short
inland camping and cruising voyage in his Albacore. There was a photo of
him sitting in a folding canvas "deck" chair perched precariously on the
deck.


I have been known to stand on the foredeck, occasionally with a drink in
my hand, and this summer I did a cruise of about 90 NM on the east coast
of England. I usually day sail however as after 8 or 10 hours under
way, I like my creature comforts :-)
However I doubt a cruising dingy needs to be as intricately rigged as a
racing dingy unless the crusing dingy has a planing hull, and that would
be a racing/crusing dingy like the Wayfarer.

I also race Wayfarers although as I don't own one I don't cruise in one.
An Albacore in racing trim is a long way from being an ideal cruising
dinghy, but if one eliminates all the racing refinements and go-faster
gadgets of the last 40 years and outfit and rig the boat in a style that
Uffa Fox would recognise, it is quite practical for coastal day sailing.
Sleeping on board however would not be a restful experiance. None of
my secondary sail controls (vang, outhaul, cunningham, jib tensioner
etc.) are lead to the helmsman, they are the crew's job.

Given a 10.5 sq m bermudan mainsail and a total sail area of about 15 sq
m (OP stated: 18' cruising dinghy, main 10,5m2 (unstayed mast); Jib
around 35% of SA ) I think if it isn't a planing hull, it will sail
under in the first decent breeze. If it has a planing hull form then
add a bowsprit, an assymetric and some trapeze wires and you'd have an
outright racing machine. To control 15 sq m of bermudan (marconi) rig
on an 18' hull in anything more than a light breeze, I reckon you need
either a super powerful vang or a good traveller system. If the OP was
considering a spritsail or boomless lug sail, it would do away with the
complex controls.



In "Dinghies for all Waters",
Eric Coleman strongly recommends a heavier, high freeboard, dingy for
crusing as a light responsive boat is too lively for relaxed crusing. He
prefered converted small fishing boats for cruising to racing boats. I
belive his Roamer design was well accepted among British dingy cruising
sailors. I've seen a photo of one on the Internet.


The trouble with displacement dinghies for cruising is they are so slow
that they cant get out of their own way if they are small enough for the
crew to manhandle on a beach. You need 15' length to make 5 knots and
that will be very heavy for a two man crew to haul out and impossible to
lift. If its big enough to have a decent hull speed, its the size of a
small yacht, in which case you might as well have a cabin, cruise in
comfort and not call it a dinghy. A slow dinghy may not be able to
reach shelter before the weather deteriorates.

Reading about the Albacore I realized I had forgot a useful feature of a
jib is the ability to drift with the sails hove to while eating, etc. I've
done that between heats at regattas, and for jumping overboard to cool
off.

I'd not trust a hove to Albacore to stay put for long ecough to swim.
One gust and you'll find it on the other tack sailing away into the
distance. If its squally you really dont want the jib aback unless you
want to swim *with* the boat. Works fine for eating however.

While I'm on this topic I'd like to suggest for the home builder an
inexpensive wooden boom with an X cross section, a design pioneered by TF
Jones and described in his book "New Plywood Boats". He's had one on his
catamaran for some time. He describes inexpensive home made hardware for
the boom as well. I don't think his boom is made of plywood but I would
think it possible.

I am still using a wooden boom. Rectangular section about 2"x4" with a
groove for the boltrope in the top. I belive it to be original although
I cant prove it was in use more than 30 years ago.

snip
'Stingo' Albacore #1554 - 15' Uffa Fox designed, All varnished hot
moulded wooden racing dinghy circa. 1961



There was a hot mouled plywood Albacore here in Ottawa, unique and very
attractive boat. The layers of plywood strips are laid 45 deg or so to the
waterline and 90 deg or so to each other. Light, strong, long lasting
construction.

Must haver been a MK 1 Fairey marine hull originally with the stern
decked in. Mine is a MK 2 hull with the outer veneer running fore and
aft. The inner veneers are 60 deg or so to each other. Extremely
durable so long as you dont leave standing fresh water anywhere in the
bottom.


--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
[dot]=.
*Warning* SPAM TRAP set in header, Use email address in sig. if you must.
'Stingo' Albacore #1554 - 15' Uffa Fox designed, All varnished hot
moulded wooden racing dinghy circa. 1961

Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
The Perfect Dinghy wanted Pete Cruising 17 May 11th 04 02:52 PM
Dinghy Thief Apprehended in Mazatlan (long) mike ASA 24 May 6th 04 07:53 PM
Skull Creek Marina complaint Aaron Cruising 8 October 14th 03 08:33 PM
What's the best dinghy for cruising and why? Harvey Porter Cruising 15 August 22nd 03 01:37 AM


All times are GMT +1. The time now is 06:52 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 BoatBanter.com.
The comments are property of their posters.
 

About Us

"It's about Boats"

 

Copyright © 2017