Re: Micro sail plan
So are we looking at the traditional junk sail or the Bolger Chinese
gaff rig?
The traditional junk sail is a balance lug type with a portion of the
sail ahead of the mast. Not a good idea on a mast right in the bow.
I believe Martin Robert's Applecross has the mast located right up
against the forward bulkhead. To me that makes more sense, and could
support a tabernacle. The questions would remain:
1. Is there enough space ahead in the bow well to allow the mast foot to
swing upwards and clear the bow? Especially if the bow was extended to a
point like on the upgraded plans.
2. Could one shorten the foot of the mast to allow clearance if there
wasn't enough and still brace it properly? I could envision a small lead
counterweight being added, and a sturdy gate closure at the base.
The advantage of the traditional junk rig is it could be used with a
tapered mast as there are loose parrels supporting the battens and no
requirement to add jaws.
The disadvantage I think, according to Bolger is the upwind performance
of the junk rig is not as good as a gaff rig. Not a huge drawback in a
Micro if one has the benefit of a good motor location and accessibility.
Putting a lot of mast weight right up in the bow seems counter-intuitive
when going downwind compared to having it further aft?
Nels
gaff rig?
The traditional junk sail is a balance lug type with a portion of the
sail ahead of the mast. Not a good idea on a mast right in the bow.
I believe Martin Robert's Applecross has the mast located right up
against the forward bulkhead. To me that makes more sense, and could
support a tabernacle. The questions would remain:
1. Is there enough space ahead in the bow well to allow the mast foot to
swing upwards and clear the bow? Especially if the bow was extended to a
point like on the upgraded plans.
2. Could one shorten the foot of the mast to allow clearance if there
wasn't enough and still brace it properly? I could envision a small lead
counterweight being added, and a sturdy gate closure at the base.
The advantage of the traditional junk rig is it could be used with a
tapered mast as there are loose parrels supporting the battens and no
requirement to add jaws.
The disadvantage I think, according to Bolger is the upwind performance
of the junk rig is not as good as a gaff rig. Not a huge drawback in a
Micro if one has the benefit of a good motor location and accessibility.
Putting a lot of mast weight right up in the bow seems counter-intuitive
when going downwind compared to having it further aft?
Nels
--- Inbolger@yahoogroups.com, "rodcahill@..." <rodcahill@...> wrote:
> 2. Would the tappered mast be strong enough to support a junk sail
>
> Thanks in anticipation,
>
> Rod Cahill
>
Just the postal address Rod. Or fax. There's email too, but I wouldn't. I take it that you're building the standard Micro, without the Nav cabin and Chinese Gaff sails? If so you won't need the industrial pipe main mast. The bow tabernacle configuration may be instructive though (as all the rest of that design), or perhaps you could better adapt the bow tabernacle for a wooden mast from the Long Micro? PB&F, or others here will know. How soon before you're at the tabernacle/mast building stage? Micro2 plans are meant to alter an existing boat - you might leave the mast aside for now, do the bow transom minimally for now if you must, then cut and fit the Micro2 tabernacle, bow slap pad, and any other mods later.
Graeme
Graeme
--- Inbolger@yahoogroups.com, Rpd Cahill <rodcahill@...> wrote:
>
> Graeme,
> What is the PB&F website address or is there only a postal address?
>
> Thanks,
>
> Rod
>
Graeme,
What is the PB&F website address or is there only a postal address?
Thanks,
Rod
From:graeme19121984 <graeme19121984@...>
To:bolger@yahoogroups.com
Sent:Wed, 17 March, 2010 4:44:36 PM
Subject:[bolger] Re: Micro sail plan
Rod,
Flying Dutchman LOA 6057mm; BOA 1780; Hull weight 130kg; Sail Area main 10.2sqm, genoa 8.4sqm, spinnaker 20sqm; Crew weight 170kg. Static RM on ear (very roughly) about 452kgm [rm hull on ear 130x0.6m + rm crew on trapeze 170(1.2+1m)]. Luff=Mast7.6m-0.6 [mainSA10.2/Luff7=Foot/2=1.45] Foot=2.9. Leach=7.5. CSA height above foot=2.5m, above deck=3.1, above cob plane=3.5. 452kgm/3.5m=129kg. That's 129kg applied to the mast 3.1m up from it's base, or 284lbs at 10.2ft.
Note how the FD mast section tapers smoothly from the heel to top without swelling near the lower end. Rest the mast horizontally supported at heel and top and have someone, or an adult and child weighing in at 129kg, gingerly carefully sit on the mast 3.1m from the heel. Careful. Note the amount of bend! And get off before it's too great and is permanent.
The FD mast is stayed, and although the Micro CSA is lower on the sail the standard sail is a litttle larger and it's still too great for the FD mast; and not only this, nor only because the Micro is more burdensome, stiffer, and therefore will stand up to stronger wind loads (all of which the free standing must must accomodate). Further, re the thin sectioned smooth tapering FD mast: there is the question of bury and the much greater bending moment about the pivot of the proposed tabernacle of the Micro unstayed mast. This is also why Michalak mentions he has tabernacles all heavily built and heftily through-bolted. Say for the same FD loadings the length below the pivot/partner is only 0.6m to the heel. The load applied at this FD mast fulcrum will be about 800kg, so the load at the *thinner* sectioned mast pivot will be climbing up to the ton. Then there's dynamic loads, and the bigger Micro 119sqft (11sqm) mainsail having CSA 7ft (2.1m) above the mast pivot plane. The Micro unstayed mast is meant to bend under load automatically so flattening the sail and reducing the load whereas in the stayed FD this is manual. Micro's sail is also flattened by hardening the snotter to push out the sprit boom, whereas an unsayed FD mast is likely to bend too easily like a banana about the snotter attachment (bow and arrow). You could try and sketch out some kind of running backstays for the FD mast, but they'd probably be a real bother - that sprit is long.
What we should do is work back the other way from the hull RM of a
fully laden stiff Microhttp://www.boatdesign.com/postings/pages/knockdown.htm
to be sure of the loadings, however I still think an unstayed FD mast flying Micro's rig won't.
I suggest getting the upgrade plan sheet for Micro2 from PB&F, IIRC @ USD50. Not available duckflat!
Graeme
--- Inbolger@yahoogroups.com, "rodcahill@..." <rodcahill@...> wrote:
>
> Hi again from Canberra, Australia,
> My Micro is progressing well and now have all bulkheads, bow, transom, and sides framed and together plus all the bottom except for the last panel at the bow end. I am making a tabernacle similar to the long micro which will extend above the deck 2' and about the same below the height of the deck. Diameter of mast base is 6cm, or just a bit less than 2.5 inches. The tabernacle will be built into the bow, approximately one foot forward of original position. Mast partners will be 3"x3" oregon. I have acquired a tappered mast 7.6 metres long from a flying dutchman.
> My questions are:
> 1. Should this mast be adequate for the standard mainsail, and
> 2. Would the tappered mast be strong enough to support a junk sail
>
> Thanks in anticipation,
>
> Rod Cahill
>
------------------------------------
Bolger rules!!!
- NO "GO AWAY SPAMMER!" posts!!! Please!
- no cursing, flaming, trolling, spamming, respamming, or flogging dead horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
- Pls add your comments at the TOP, SIGN your posts, and snip away
- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
- Unsubscribe: bolger-unsubscribe@yahoogroups.com
- Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.comYahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/bolger/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/bolger/join
(Yahoo! ID required)
<*> To change settings via email:
bolger-digest@yahoogroups.com
bolger-fullfeatured@yahoogroups.com
<*> To unsubscribe from this group, send an email to:
bolger-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
Rod,
Flying Dutchman LOA 6057mm; BOA 1780; Hull weight 130kg; Sail Area main 10.2sqm, genoa 8.4sqm, spinnaker 20sqm; Crew weight 170kg. Static RM on ear (very roughly) about 452kgm [rm hull on ear 130x0.6m + rm crew on trapeze 170(1.2+1m)]. Luff=Mast7.6m-0.6 [mainSA10.2/Luff7=Foot/2=1.45] Foot=2.9. Leach=7.5. CSA height above foot=2.5m, above deck=3.1, above cob plane=3.5. 452kgm/3.5m=129kg. That's 129kg applied to the mast 3.1m up from it's base, or 284lbs at 10.2ft.
Note how the FD mast section tapers smoothly from the heel to top without swelling near the lower end. Rest the mast horizontally supported at heel and top and have someone, or an adult and child weighing in at 129kg, gingerly carefully sit on the mast 3.1m from the heel. Careful. Note the amount of bend! And get off before it's too great and is permanent.
The FD mast is stayed, and although the Micro CSA is lower on the sail the standard sail is a litttle larger and it's still too great for the FD mast; and not only this, nor only because the Micro is more burdensome, stiffer, and therefore will stand up to stronger wind loads (all of which the free standing must must accomodate). Further, re the thin sectioned smooth tapering FD mast: there is the question of bury and the much greater bending moment about the pivot of the proposed tabernacle of the Micro unstayed mast. This is also why Michalak mentions he has tabernacles all heavily built and heftily through-bolted. Say for the same FD loadings the length below the pivot/partner is only 0.6m to the heel. The load applied at this FD mast fulcrum will be about 800kg, so the load at the *thinner* sectioned mast pivot will be climbing up to the ton. Then there's dynamic loads, and the bigger Micro 119sqft (11sqm) mainsail having CSA 7ft (2.1m) above the mast pivot plane. The Micro unstayed mast is meant to bend under load automatically so flattening the sail and reducing the load whereas in the stayed FD this is manual. Micro's sail is also flattened by hardening the snotter to push out the sprit boom, whereas an unsayed FD mast is likely to bend too easily like a banana about the snotter attachment (bow and arrow). You could try and sketch out some kind of running backstays for the FD mast, but they'd probably be a real bother - that sprit is long.
What we should do is work back the other way from the hull RM of a
fully laden stiff Microhttp://www.boatdesign.com/postings/pages/knockdown.htm
to be sure of the loadings, however I still think an unstayed FD mast flying Micro's rig won't.
I suggest getting the upgrade plan sheet for Micro2 from PB&F, IIRC @ USD50. Not available duckflat!
Graeme
Flying Dutchman LOA 6057mm; BOA 1780; Hull weight 130kg; Sail Area main 10.2sqm, genoa 8.4sqm, spinnaker 20sqm; Crew weight 170kg. Static RM on ear (very roughly) about 452kgm [rm hull on ear 130x0.6m + rm crew on trapeze 170(1.2+1m)]. Luff=Mast7.6m-0.6 [mainSA10.2/Luff7=Foot/2=1.45] Foot=2.9. Leach=7.5. CSA height above foot=2.5m, above deck=3.1, above cob plane=3.5. 452kgm/3.5m=129kg. That's 129kg applied to the mast 3.1m up from it's base, or 284lbs at 10.2ft.
Note how the FD mast section tapers smoothly from the heel to top without swelling near the lower end. Rest the mast horizontally supported at heel and top and have someone, or an adult and child weighing in at 129kg, gingerly carefully sit on the mast 3.1m from the heel. Careful. Note the amount of bend! And get off before it's too great and is permanent.
The FD mast is stayed, and although the Micro CSA is lower on the sail the standard sail is a litttle larger and it's still too great for the FD mast; and not only this, nor only because the Micro is more burdensome, stiffer, and therefore will stand up to stronger wind loads (all of which the free standing must must accomodate). Further, re the thin sectioned smooth tapering FD mast: there is the question of bury and the much greater bending moment about the pivot of the proposed tabernacle of the Micro unstayed mast. This is also why Michalak mentions he has tabernacles all heavily built and heftily through-bolted. Say for the same FD loadings the length below the pivot/partner is only 0.6m to the heel. The load applied at this FD mast fulcrum will be about 800kg, so the load at the *thinner* sectioned mast pivot will be climbing up to the ton. Then there's dynamic loads, and the bigger Micro 119sqft (11sqm) mainsail having CSA 7ft (2.1m) above the mast pivot plane. The Micro unstayed mast is meant to bend under load automatically so flattening the sail and reducing the load whereas in the stayed FD this is manual. Micro's sail is also flattened by hardening the snotter to push out the sprit boom, whereas an unsayed FD mast is likely to bend too easily like a banana about the snotter attachment (bow and arrow). You could try and sketch out some kind of running backstays for the FD mast, but they'd probably be a real bother - that sprit is long.
What we should do is work back the other way from the hull RM of a
fully laden stiff Microhttp://www.boatdesign.com/postings/pages/knockdown.htm
to be sure of the loadings, however I still think an unstayed FD mast flying Micro's rig won't.
I suggest getting the upgrade plan sheet for Micro2 from PB&F, IIRC @ USD50. Not available duckflat!
Graeme
--- Inbolger@yahoogroups.com, "rodcahill@..." <rodcahill@...> wrote:
>
> Hi again from Canberra, Australia,
> My Micro is progressing well and now have all bulkheads, bow, transom, and sides framed and together plus all the bottom except for the last panel at the bow end. I am making a tabernacle similar to the long micro which will extend above the deck 2' and about the same below the height of the deck. Diameter of mast base is 6cm, or just a bit less than 2.5 inches. The tabernacle will be built into the bow, approximately one foot forward of original position. Mast partners will be 3"x3" oregon. I have acquired a tappered mast 7.6 metres long from a flying dutchman.
> My questions are:
> 1. Should this mast be adequate for the standard mainsail, and
> 2. Would the tappered mast be strong enough to support a junk sail
>
> Thanks in anticipation,
>
> Rod Cahill
>
On Tue, Mar 16, 2010 at 2:18 PM, alefoot <dgw@...> wrote:
spar. The other important purpose of that spar (beyond being a mast)
is to act as an elevated sheeting staff, which holds the sheetlets for
the gaff and the battens. This is the reason, I think, that the plans
call for this spar to be untapered.
>Bear in mind that the Micro Navigator mizzen mast, is a dual purpose
> You might however be able to use a section of the FD spar as a Mizzen mast for the standard [unstayed sprit-boomed 'leg of mutton'] rig.
>
spar. The other important purpose of that spar (beyond being a mast)
is to act as an elevated sheeting staff, which holds the sheetlets for
the gaff and the battens. This is the reason, I think, that the plans
call for this spar to be untapered.
Your mast sounds way over built.
I think Phil over designed masts. I chose my mast thicknesses by guess and by golly after carefully studying every mast design Phil had published. Solid masts are heavy, but must be nearly as thick as hollow built masts which are little more difficult to build than solid masts.
ROGUE's (8,000lbs displacement, 26'x7.5'x1' 600lbs waterballast, 700lbs lead in bottom ten inches of leeboards which increase draft to 6') masts are 5.5" x 24' and 6" x 27', has freestanding hollow masts masts built of that special spar wood Lowe's and the like sell called SPF. I only chose Spruce and Pine because fir was too heavy for my purposes. By careful choosing and judicious slicing on the tablesaw I got virtually knot free staves. Stave thickness is 1 1/8" plus six oz epoxy fiberglass on the inside (partly for strength and mostly to waterproof masts that serve as vents. the foremast vents the composting head - walnut throne), polyester shirt material epoxyed to the outside for paint and to add some protection to the soft wood. I wanted the outside "glass" to be at least as flexible as the wood. Thickened epoxy glue joints.
These masts are way way overbuilt. They flex not at all. 1" for the main, and 5/8" for the fore would have been more than adequate with a large safety margin. The masts were birdsmouth built eight sided planed and sanded to round. Left octogonal at the bottom to be clamped in. To make the birds mouth just set table saw to 45* raise to make a cut half the width of the stave. Flip the stave and run it through again. Scarf your staves to full length and cover with fiberglass if desired beforehand, in fact before cutting them to the desired width. Tapering is simple. Just take off the necessary amount from the flat side after cutting the birdsmouth (one eighth of the mast taper at each mastheight).
Eric
I think Phil over designed masts. I chose my mast thicknesses by guess and by golly after carefully studying every mast design Phil had published. Solid masts are heavy, but must be nearly as thick as hollow built masts which are little more difficult to build than solid masts.
ROGUE's (8,000lbs displacement, 26'x7.5'x1' 600lbs waterballast, 700lbs lead in bottom ten inches of leeboards which increase draft to 6') masts are 5.5" x 24' and 6" x 27', has freestanding hollow masts masts built of that special spar wood Lowe's and the like sell called SPF. I only chose Spruce and Pine because fir was too heavy for my purposes. By careful choosing and judicious slicing on the tablesaw I got virtually knot free staves. Stave thickness is 1 1/8" plus six oz epoxy fiberglass on the inside (partly for strength and mostly to waterproof masts that serve as vents. the foremast vents the composting head - walnut throne), polyester shirt material epoxyed to the outside for paint and to add some protection to the soft wood. I wanted the outside "glass" to be at least as flexible as the wood. Thickened epoxy glue joints.
These masts are way way overbuilt. They flex not at all. 1" for the main, and 5/8" for the fore would have been more than adequate with a large safety margin. The masts were birdsmouth built eight sided planed and sanded to round. Left octogonal at the bottom to be clamped in. To make the birds mouth just set table saw to 45* raise to make a cut half the width of the stave. Flip the stave and run it through again. Scarf your staves to full length and cover with fiberglass if desired beforehand, in fact before cutting them to the desired width. Tapering is simple. Just take off the necessary amount from the flat side after cutting the birdsmouth (one eighth of the mast taper at each mastheight).
Eric
--- Inbolger@yahoogroups.com, Bruce Hallman <hallman@...> wrote:
>
> >a piece of straight tubing. Maybe somebody else can chime in with the diameter and wall thickness of the recommended tubing.
>
> The Micro Chinese Gaff rig mainmast, (I own one) is designed as 4"
> stock aluminum pipe. That was kind of pricey, I asked and PCB said I
> could use a built up mast made from wood. I sandwiched three courses
> of plain old 2x6 home depot lumber, and rounded her off to about 4
> 1/2" diameter with a Skilsaw and belt sander. Easy job, and cheap
> too. The mast needs to be untapered because of the jaws on the gaff
> and battens. Maybe it could be tapered above the gaff jaw, but for
> simplicity it is not. Really it is just rugged simplicity.
>
> The mizzen mast, which serves double duty as a rigging staff to
> elevate the sheaves for the gaff and batten sheetlets for improved
> sheeting angle vis a vis the classical junk rig geometry, is also
> untapered.
>
--- Inbolger@yahoogroups.com, "rodcahill@..." wrote:
1. No
2. No
You might however be able to use a section of the FD spar as a Mizzen mast for the standard [unstayed sprit-boomed 'leg of mutton'] rig.
More complete answers as given by other posters.
>I have acquired a tappered mast 7.6 metres long from a flying dutchman.Short answers:
> My questions are:
> 1. Should this mast be adequate for the standard mainsail, and
> 2. Would the tappered mast be strong enough to support a junk sail
1. No
2. No
You might however be able to use a section of the FD spar as a Mizzen mast for the standard [unstayed sprit-boomed 'leg of mutton'] rig.
More complete answers as given by other posters.
>a piece of straight tubing. Maybe somebody else can chime in with the diameter and wall thickness of the recommended tubing.The Micro Chinese Gaff rig mainmast, (I own one) is designed as 4"
stock aluminum pipe. That was kind of pricey, I asked and PCB said I
could use a built up mast made from wood. I sandwiched three courses
of plain old 2x6 home depot lumber, and rounded her off to about 4
1/2" diameter with a Skilsaw and belt sander. Easy job, and cheap
too. The mast needs to be untapered because of the jaws on the gaff
and battens. Maybe it could be tapered above the gaff jaw, but for
simplicity it is not. Really it is just rugged simplicity.
The mizzen mast, which serves double duty as a rigging staff to
elevate the sheaves for the gaff and batten sheetlets for improved
sheeting angle vis a vis the classical junk rig geometry, is also
untapered.
Rod,
IIRC the Dutchman uses a stayed mast with spreaders and mast shaping controls. The Micro mast is free standing. Even if you wanted to stay the Dutchman mast the bow is too narrow. One of the strong points of either the stock Micro sail or the junk rig is the ability to let the sail out 90 degrees to go downwind and to let the sail run ahead of the mast when needed for safety. You don’t get those features in a stayed rig so those rigs often have to tack downwind. The mast in tabernacle/junk rig from the Micro updates uses a piece of straight tubing. Maybe somebody else can chime in with the diameter and wall thickness of the recommended tubing.
MylesJ
Rod,
I do not believe that the original mast would be strong enough to support a junk rig. The navigator plans give the size that Phil thought should be used.
Martin
On Tue, Mar 16, 2010 at 3:23 AM,rodcahill@...<rodcahill@...>wrote:Hi again from Canberra, Australia,
My Micro is progressing well and now have all bulkheads, bow, transom, and sides framed and together plus all the bottom except for the last panel at the bow end. I am making a tabernacle similar to the long micro which will extend above the deck 2' and about the same below the height of the deck. Diameter of mast base is 6cm, or just a bit less than 2.5 inches. The tabernacle will be built into the bow, approximately one foot forward of original position. Mast partners will be 3"x3" oregon. I have acquired a tappered mast 7.6 metres long from a flying dutchman.
My questions are:
1. Should this mast be adequate for the standard mainsail, and
2. Would the tappered mast be strong enough to support a junk sail
Thanks in anticipation,
Rod Cahill
Hi again from Canberra, Australia,
My Micro is progressing well and now have all bulkheads, bow, transom, and sides framed and together plus all the bottom except for the last panel at the bow end. I am making a tabernacle similar to the long micro which will extend above the deck 2' and about the same below the height of the deck. Diameter of mast base is 6cm, or just a bit less than 2.5 inches. The tabernacle will be built into the bow, approximately one foot forward of original position. Mast partners will be 3"x3" oregon. I have acquired a tappered mast 7.6 metres long from a flying dutchman.
My questions are:
1. Should this mast be adequate for the standard mainsail, and
2. Would the tappered mast be strong enough to support a junk sail
Thanks in anticipation,
Rod Cahill
My Micro is progressing well and now have all bulkheads, bow, transom, and sides framed and together plus all the bottom except for the last panel at the bow end. I am making a tabernacle similar to the long micro which will extend above the deck 2' and about the same below the height of the deck. Diameter of mast base is 6cm, or just a bit less than 2.5 inches. The tabernacle will be built into the bow, approximately one foot forward of original position. Mast partners will be 3"x3" oregon. I have acquired a tappered mast 7.6 metres long from a flying dutchman.
My questions are:
1. Should this mast be adequate for the standard mainsail, and
2. Would the tappered mast be strong enough to support a junk sail
Thanks in anticipation,
Rod Cahill