Converting a modern sloop to a lug rig

[cluttonfred]

Hi, all, here's how my brain works, I'd love some feedback.

Phil Bolger's take on a classic early cruising yacht (see link) was to give Seabird '86 (below) a dipping lug and an outboard, arguing that a sail optimized for a straight course was a reasonable compromise and a huge cost savings that suited the way many people use their boats. There was also a boomless trysail for heavy weather work. That design has always fascinated me in terms of bang for buck.

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I have recently discovered the Dobler Q17 (below and see link) and I love the simple, taped-seam-plywood, raised-deck hull design including the steel plate ballast keel with a 400 lb cast iron or lead bulb raised and lowered by a bumper jack. I am less thrilled with the masthead rig with backstay and a roller furling main inside the hollow slotted aluminum mast because I would prefer something simpler, cheaper, and easier to build myself.

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LIGHT BULB! So how about converting the Q17 to a lug rig? It could keep the stayed mast stepped on deck but much shorter, a forestay but no backstay just the shrouds cheated aft. It could have a big dipping lug with reefs like Seabird '86 as the light air/straight course sail, and perhaps a smaller standing lug (with or without boom) with reefs as the heavy weather/tacking sail. Alternatively, it could have all the sail area in a big standing lug (with or without boom) or balanced lug and perhaps a small jib.

Let the comments begin...I've got my fireproof underoos on! ;-)

 

[gonzo]

The dipping lug you show has a keel mounted mast with no forestay. A deck mounted mast without a forestay will fall down. The first modification you need to consider is to install a mast step on the keel.

 

[Igor]

Dipping lug and outboard seems to be a good combo for budget cruiser, Breton lugger from Selway Fisher is especially nice.

 

[cluttonfred]

Dipping lug and outboard seems to be a good combo for budget cruiser, Breton lugger from Selway Fisher is especially nice.

Excellent, thanks, I didn’t even know SF had a lugger.

The dipping lug you show has a keel mounted mast with no forestay. A deck mounted mast without a forestay will fall down. The first modification you need to consider is to install a mast step on the keel.

Not at all, many traditional luggers had shrouds, even multiple shrouds and ratlines, that limited how far forward the yard (and boom if there was one) could go. In practice, you weren’t giving up much since going downwind was rarely a problem and the yard became harder to control if too far forward in any case. A backstay would be a problem but a forestay and shrouds cheated aft should work just fine.

traditional lugger - Google Search https://www.google.com/search?q=traditional+lugger

 

[skaraborgcraft]

You can easily put that Q17 mast in a keel stepped tabernacle. I much prefer a balanced lug with a boom, they are far more controllable going downwind.

 

[skaraborgcraft]

For inspiration, a Michalak Jukebox boat.

 

[cluttonfred]

You can easily put that Q17 mast in a keel stepped tabernacle. I much prefer a balanced lug with a boom, they are far more controllable going downwind.

Look again...the Q17 has a retractable steel and cast iron keel below the mast, and that structure supports the mast step on at the deck.

Yes, it could be changed substantially to included a cantilever mast forward but at that point I may as well pick another design. I like the hull and cabin and keel just fine, it's only the rig that turns me off.

That said, the more I mess around with this, placing outlines of existing lugsail rigs over the same hull and aligning the masts, the more I think I'll have to stick with a jib-headed sloop rig and just simplify the details like eliminating the in-mast furling. I'll keep messing around with it though and would welcome other suggestions of simplified rigs on this hull with this mast placement.

 

[skaraborgcraft]

Yes, it could be changed substantially to included a cantilever mast forward but at that point I may as well pick another design. I like the hull and cabin and keel just fine, it's only the rig that turns me off.

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I still do not see an issue, but i do not have the drawing in front of me. Timbers running either side of the case from floor and through the deck will make a good tabernacle. You might lose some minor foot space sitting on the dunny. If you are not fixed on that rig, you could push out to the ends like on the Picara.

I modeled this design to take a ballasted drop daggerboard rather than the leeboard, to attain better stability and self righting .

 

[skaraborgcraft]

Theres always junk rig too.

What are you wanting to getting away from in the standard rig? A balanced lug is about as simple as it gets.

 

[cluttonfred]

Perhaps because what little boatbuilding experience I have is in small plywood boats, I am put off by the complexity of a stayed aluminum mast with spreaders, backstay, and roller furling inside the mast, and the multiple headsails. I started this thread thinking I would like to have some sort of lug rig (dipping or standing or balanced) but I think the mast position isn't going to work for that. In the end, the best solution will probably be to consult a pro on just simplifying the existing rig. Ideally, I'd like to eliminate the backstay and just anchor the shrouds a little bit aft, include a short tabernacle (or raised hinged mast step at) for easier trailering, eliminate the roller furling of the main in favor of a couple of ordinary reefs, and have just one roller reefing headsail. At least, I think that's what I'd like, this is all new territory for me considering the biggest boat I've built is a Bolger June Bug and the only one with a sail was Bolger Brick. ;-)

 

[Igor]

Perhaps because what little boatbuilding experience I have is in small plywood boats, I am put off by the complexity of a stayed aluminum mast with spreaders, backstay, and roller furling inside the mast, and the multiple headsails. I started this thread thinking I would like to have some sort of lug rig (dipping or standing or balanced) but I think the mast position isn't going to work for that. In the end, the best solution will probably be to consult a pro on just simplifying the existing rig. Ideally, I'd like to eliminate the backstay and just anchor the shrouds a little bit aft, include a short tabernacle (or raised hinged mast step at) for easier trailering, eliminate the roller furling of the main in favor of a couple of ordinary reefs, and have just one roller reefing headsail. At least, I think that's what I'd like, this is all new territory for me considering the biggest boat I've built is a Bolger June Bug and the only one with a sail was Bolger Brick. ;-)

Small fractional sloop could work nicely on that hull, swept back shrouds and no backstays. Check the used market.

 

[skaraborgcraft]

Perhaps because what little boatbuilding experience I have is in small plywood boats, I am put off by the complexity of a stayed aluminum mast with spreaders, backstay, and roller furling inside the mast, and the multiple headsails.

It certainly does not have to be like that, but im not sure of my own math to determine the correct spar dimensions and shrouds for a swept back shrous non-backstay rig. I dont think the mast is in a bad position if you consider the mast on the Seabird. Is there a drawing of the centre of effort of the existing rig? It would not be difficult to size an appropriate square sail to match, and one of the major advantages of the balanced lug is the amount of play in the boom and yard to shift the centre of effort to where you want it for ease of helming.

I think the Q17 is just a bigger boat, rather than more complex, than what you have built, same can be said for the Michalak types. Depending on your location, boats of this size can often be had for very little money second hand.

 

[Paul Scott]

If you try any lug with shrouds, you’re going to be sailing by the Lee at some point downwind, no? (Unless you go with a really high aspect ratio ) Same with swept back shrouds with a ‘normal’ sloop rig. Speaking as someone who has a sloop with 33 degree swept spreaders, VMG gybing downwind is a nice idea, but sometimes narrow passages and wind strength really don’t lend themselves easily to gybing down wind, unless you go jib only, and then you’ve got the same problem as a dipping lug. Micheal Storer likes to point out that standing lugs really do well (sometimes better) on the ‘bad tack’, so there’s that. I suppose running backs might help, but sometimes they’re just too much. (We have running backs too.)

Add to this the structural differences twixt a hull designed for shrouds and one designed for a freestanding mast, and you then have added weight duplicating both structural hull systems if you convert from shrouds to freestanding, in addition to nailing center of effort of the sail. General advice on a standing lug seems to be at max 25% of the mainsail in front of the mast, 75% in back to keep a satisfying sheet pressure, so you’ll likely need to move the mast position? Dipping lugs have more freedom there, but then you need to deal with dipping the thing, which, depending on your druthers, can be as fraught as sailing downwind bye the Lee. (Although if you’ve raced, say, Lasers or Finns enough, sailing bye the Lee will be 2nd nature- but still, an accidental gybe might excessively amuse your shrouds….)

(It’s always something.)

You probably need to consult an engineer.

 

[skaraborgcraft]

If you try any lug with shrouds,

Add to this the structural differences twixt a hull designed for shrouds and one designed for a freestanding mast,

I dont think he wants shrouds with a lug, just wanted a backstay free sloop.
As for structural considerations, a ring frame in contact with the mast step/tabernacle is all that is required, yes it will add some weight maybe equal to few feet of anchor chain, no biggie if done right,IMO, it could join in with the other bonded furniture that supports the hull in line with the galley box half bulkhead.

 

[skaraborgcraft]

General advice on a standing lug seems to be at max 25% of the mainsail in front of the mast, 75% in back to keep a satisfying sheet pressure,.

Satisfying sheet pressure? I can speak from experience taking a gaff rig downwind in strong conditions that sheet and tiller loads were excessive, as well as the occasional dipping of the boom. The same conditions under a lug where almost the divide was 45-55 either side of the mast was light sheet, light helm and reduced rolling. Gaff are pretty naff when reefed down too, as the area is too far aft, meaning more helm loads.