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Adding a Jib to the Sprit Rig

My current sail

My Current sail is a 62 sq ft sprit sail. The whole rig is slightly unbalanced because this rig adds more sail behind the centre balance. I had lengthened the boom by about a foot and the point is higher. I think adding a small jib might actually improve my sail balance.

The balance of this boat is very sensitive to where I sit. A small shift of position makes a big difference in the balance.

I wrote an article on Sprit sails. The more I know about them, the better I like sprit sail

Bolger's small boat rigsBolger's small boat rigs

Bolger's small boat rigs. He had considered adding a jib to a spritsail. It would be a Sloop rig!!

"By adding a jib to the basic boomless spritsail, some extra area is added in an efficient form, without any multiplication or lengthening of the few short spars. The jib is a good airfoil in its own right and the draft off it improves the drive of the mainsail. The position of the jib is perfect for a leading-edge device. The spritsail is prone to twist on account of the difficulty of keeping the peak up tight. But the jib compensates for the twist to some extent. Taking the jib off doesn't affect the balance of the rig as much as might be thought. If it's sheeted correctly 10 or 12 degrees out of the centerline, the pull of the sheet tends to swing the bow into the wind. The forward position of the sail has a surprisingly small tendency to knock her bow off the wind. "

Planning sketch

The yellow is the proposed Jib. I measured the dimensions of the drawing provided by Chesapeake Light Craft on the Skerry page and drew in the modifications. The blue roughly represents my current sail, I think it is actually a bit higher off the boat. I plan to bring the end of the line to the middle bulkhead. I had drilled holes to attach my bumper noodles so I don't need to modify anything on the boat. Eventually I guess I will put some for of cleat.

The area of the jib is going to be about 18-20 square feet. My mast is overbuilt and quite stiff so I don't think there will be any particular problem.
Since I sit just behind the seat bulkhead, I will not have to move in order to sheet in the jib. I suppose I will have to figure out a nice way of attaching it so I can instantly release it. I don't want to cleat my mainsail so I will have to cleat the Jib.

My sprit has a boom while Bolgers description is for a loose footed sail. I guess I will just have to experiment.

reinforced bow
Bow seat reinforcement During my build I had added an extra piece of ply to the bow and stern seats. I also have a reinforcement and attachment in the bow, you can see the piece of mahogany. That backs up and supports the ring for the front painter. I have also added a small brass attachment. I hope to use that for the jib attachment. If the screws pull out I will add a ring on the seat with washers and nuts and bolts.
polytarp gets spread on floor
Here we go again.

Crew inspects the polytarp. Its a good material for experimenting. This particular sheet is very thin and light. I went for colour both to match the existing sail and because I like to use bright colours. I'm almost always out alone and bright sails make me easier to notice.
I trimmed off extra material so it would be easier to handle. The trimmed sheet will be used for a cover for the Puddle Duck Racer I'm building.

Polytarp gets measured and marked.

I had measurements for all sides from my sail drawing. Since it is to scale I had just measured and scaled up. Not terribly precise but since I don't have strong opinions about a jib I'm not sure it matters. The only concern I had was that it would fit in the space and would not be too large. I was also concerned that the line to the bulkhead would not be at an odd angle.

The luff is to the straight of the fabric since it will be under some tension. The foot is close to 90 degrees so will also almost be straight of fabric. I have added enough fabric to fold the edge twice. No need here to add binding.

Corner patches for skerry jib
Corner patches

Corner patches are cut for the reinforment. I follow the same alignment of the fabric as the sail. I stitched the 2 patch pieces together before I sew them on the sail.

Skerry jib being sewn
Sewing the jib

This is a very simple sail. The edges get turned over and sewn. When I come to the corners I add the patches. I also trim a layer off the ends so that I dont end up with 10 plus layers at the corners. I eventually stitched 3 times, this made the edging a bit stiffer and I hope stronger. I am not planning to put any rope inside or out to strengthen the edges. I have not attempted to add any shape to the sail. It is completely flat. If this experiment works I will look into improving the shape of the sail but I'm not sure yet that this will work or improve the current rig at all. I was quite pleased with the existing orange sail and I know that when it comes time to replace it I will pay attention to shaping the sail to improve performance.

Skerry jib being sewn
Made under stict quality control

Highest standards of quality control are maintained in the sail loft. Each step in the process always start with -Remove cat from sail.

Skerry jib corner detail
Corner detail

One of the corners showing patches and stitching. The tip was trimmed and stitched. Grommet still needs to be applied. I only put 2 layers to the corner patches. My other sails had 4-5 layers I hope this is enough. I don't think this sail will be under alot of stress though. The sail is very light. I will put light lines on the ends so that the weight of them does not interfere with the sail billowing freely.

Skerry jib
final shape

All I need to do now is apply the grommets. I will use the soldering iron to melt a hole in each corner and quickly put in the grommet.
I have an extra block I can use at the top of the mast to haul the sail up. I will add a cleat on the mast if this works. Until I've tested it I can attach it to the downhaul cleat.

I'll have to be patient and wait until spring to test this sail. SIGH!! Have you seen by boat club page icicles?

Skerry jib Skerry jib set up

My boat with its sails up, the jib fits well on the boat. Line at the end of the sprit prevents jib from getting hooked on the end. That is one of the problems of this sail. I think in the future I will try a smaller jib that does not touch the sprit. If I ran a line in front of the mast from side to side, I could make the jib self tacking. To be continued.

Skerry jib
Jib line is attached on inside "stem". I have a small block at the top of the mast to raise the sail. So far I have just attached the halyard to the same cleat that secures the downhaul. This was for testing only.
Skerry jib
Jib line is attached to oarlock. Oarlock is tied in place in case it gets pulled out. Eventually I will install a cleat. For the present I either twist the jib line a few times around the oarlock and it holds. If there is alot of wind, then just loop it around the oarlock and hang on to the end in case I need to spill wind quickly.
Skerry jib
Jib has quite a good shape and improves performance significantly.
The main difficulty is getting used to another sail. It is also quite likely to get tangled up. I added the rope on the sprit to remove a source of trouble. I have to keep the various lines very tidy otherwise they tangle.
I have not dared take the jib out in high wind yet. I will wait till I have sorted out the various cleats and ropes better. It is a great improvement probably because it improves airflow around the mainsail, and its very easy to drop the sail if needed. I used a bowline to tie the sheet to the sail. It seems to work.

Short video showing the jib in use. The wind is coming from behind and the jib is pushed out using a boat hook. Wind is about 8 knots and the speed is good. It's hard to take photos of the jib in use while underway because it is hidden by the main sail usually.

self tending jib
In my club there is a boat that has a self tending jib. He just sets it and can go out and when he tacks the jib just comes around. This might be the solution for my jib control issues. I have a larger photo with better resolution and description here.
Skerry jib

The jib has improved the balance of the rig and makes handling easier.

This is the current incarnation of the rig. I have set up a small halyard and its easy to drop and haul up. I have also set up 2 camcleats on each side of the middle seat. That works well too. The only problem I'm having is that the jib sometimes gets caught up in the end of the sprit when I tack. I keep a boathook handy to sort that out when it happens. It has really improved the sailing of the skerry. I can point better upwind and certainly go better. I never seem to go much faster than 5 knots, I guess that's my hull speed.

After dropping the jib I can use the halyard to pull up the boom. I just attach the end of the halyard to the end of the boom, loosen the snotter to release the tension on the sprit and pull the boom up against the mast. It's an easy way of getting the boom out of the way if I want to row when the wind has died off and I'm stuck in the middle of the lake just bobbing.

With this rig I can heave to and stay pretty much put quietly drifting. It's a bit uncanny this parking of the boat.

Read about building the Skerry boat.


Links to the [hull part 1] [hull part 2] [mast] [rudder and centreboard] [sail] [oars]
[cleats] [ daggerboard well and mast step ]

emails: Christine

This web site reflects my personal ideas and doesn't represent anyone else's point of view.