About the Centerboard
Climbing on the Lift
Downwind Sail Trim
The spritsail, spars and rigging that accompany Crawford Boat Building's MELONSEED SKIFF are an example of simplicity and efficiency. It is unlikely that any rig is the equal of the sprit rig in providing performance with a minimum of hardware and fuss.
The following is a illustration followed by a description of the component parts, their assembly and function:
click on the boom or mast for more...
Feed the 1/8” braided Dacron line through the grommet as shown.
Put the two ends through the hole in the top of the mast.
Put your thumb between the two lines, and take the line on the left side of your thumb and pass it through the left side of the grommet. Do the same with the right side line and put it through the right side of the grommet.
Keeping the lines neat “right to left” make more passes through the hole with the lines as seen next.
IMPORTANT: You will tie off the excess with a square knot, but before you do, be sure that the sail is NOT pinched up tight against the mast, and that the luff runs STRAIGHT up the mast. The luff should be stretched fairly tight but not overly tight. Each lace line should allow the luff to be spaced evenly away from the mast.
Cut off the excess line with a heat gun, or if you don’t have one, trim it with a scissors and then VERY carefully burn the ends of the line to seize them and keep them from fraying. I also melt the line (tricky!) in one side of the knot just a tiny bit so that it won’t become undone.
Technically a SPRIT BOOM ... This has a slot in the end that goes forward and a hole with a snap attached to it in the aft end. To get optimum performance on all points of sail the boom will be set on the opposite side of the sail from the sprit - (It doesn't matter which side you put either spar on.) This causes the least average overall interference to the shape of the sail. You may set both spars on one side of the sail if you wish although you will get a better shape sail on one tack than the other. (This can only be useful if you are going to be on mostly one tack over a sustained distance.) Attach the boom to the sail by clipping the snap on the end of the boom to the grommet on the CLEW of the sail. The clew is the corner of the sail that is on the bottom of the sail closest to the transom.
The forward end of the boom is attached to the mast with another small line called a Boom SNOTTER. This short line should be permanently on the mast for sake of convenience. It has either a knot or a loop in one end, and goes down through the eye strap to the jamb cleat. Put the knot or loop into the SLOTTED of the boom, and tension the boom snotter according to the wind strength.
The item from which the rig gets it's name. This is a 10' stick with a spike in the upper end and a line (called a snotter) attached through a hole in its bottom end. Setting this into the rig is extremely simple, but adjusting the upward tension against the sail top (PEAK) is the single most important adjustment you will make. It goes like this: Grab the sail peak and insert the spike into the rope loop that is sewn into the sail. Push the sprit upward. Tie off the snotter to the cleat located on the mast nearby. Now this is where you can get the most out of the rig's performance potential. The more the wind, the stronger the sprit tension! If you ever see sag lines in the sail because the sprit is not tensioned enough, then you are not getting maximum performance. Remember, soft wind, soft sail .... stiff wind, stiff sail. There are some very technical reasons for this, but that's a two beer conversation. A simple rule of thumb is to always OVERTENSION the sprit a bit anyway because the snotter seems to slip a bit naturally. When sailing to windward, you should never see sag lines in the sail in any direction.
A quadrilateral (square) sail of dacron weighing approx. 4-5 oz. per yard. It has numerous holes called grommets set into it, to which line (rigging) is attached. The edge that is set against the mast is called the LUFF. Using the light 15" light lines provided, tie the luff to the mast so that sail stands evenly about "' away from the back edge of the mast. Tie each of these LACE LINES tight with a good firm square knot. Tie the top most grommet to the hole in the top of the mast using a longer (24") lace line, and go through the hole at least twice and tie off very well. At no point should the sail luff appear crimped!
The corner of the sail that is at the bottom of the luff is called the TACK. Hanging down from the tack is a line attached to the sail called the DOWNHAUL. Now refer back to the mast hardware descriptions and this will start to come together. Tie the downhaul line to lowest cleat on the mast, the one just above deck level, the downhaul cleat. Be sure to tension the luff fairly tight. Good luff tension is very important. The sail is on the mast now so let's continue to rig it up.
A 10' length of solid wood which sets into the boat and is held in place by the mast step at its bottom (heel), and the mast partner at deck level. It has four pieces of hardware fastened to it. Starting from bottom to top they are:
1. A small 3" cleat that the sail downhaul is tied to. On the opposite side of the mast are the other three pieces.
2. A second cleat to tie off the boom snotter.
3. An eye strap to turn this snotter.
4. Further up the mast, a cleat for the sprit snotter.
Don't be confused by the unfamiliar nautical terminology at this point. Just notice the four pieces of hardware. The rigging will be described later.
A 25' length of dacron line with a snap on one end. Snap the sheet onto either the grommet in the clew (along with the boom end snap) or to the snap itself. Newer boats have a RING attached to the bottom of the boom. Snap the sheet to this ring. Run the other end of the sheet through the block on the rudder head and IMMEDIATELY tie a figure eight-knot in the end.
One of the wonderous features of the Melonseed Skiff is that with just a little practice, this rigging drill can be accomplished in
ONLY A MINUTE OR TWO!!!
Now that you have accomplished all this, take fifteen knots of wind and two hours of spare time. Mix well. Apply as often as necessary! Caution; continuous use of this rig and boat can lead to addictive sailing behavior.
Operating and understanding the Melonseed Centerboard:
The centerboard is a plate of 1/2" PVC plastic that is held in place in the centerboard trunk by a bolt, rubber washers, metal washers and a lock nut on its forward lower end. Actually, the board does not ride on the bolt as you might imagine from a visual inspection, but there is a piece of PVC plastic tube that acts as a ‘bushing” around the bolt. There is Sika-flex 291 adhesive sealant between the rubber washer and the fiberglass centerboard trunk. It is a very strong and watertight system that should endure well as time goes on because the friction is really minimized by the water lubricated PVC on PVC system.
The board will rise by itself if you run aground or strike an underwater object.
The string that raises and lowers the board is called a centerboard “pennant”. The pennant is attached to the top aft end of the board by a very simple system of holes and a knot. Once a year or so, check the condition of the pennant where it connects with the board to be sure there is no wear on the pennant.
There are two (permanent ??) magic marker marks on the pennant to indicate the depth settings of the centerboard. With the board pulled up all the way there should be one mark on the pennant at 12” back from the cleat, and another one at 22” back.
If you lower the board and cleat the pennant off at the first mark you will have a “half depth board” with a draft of about 16" – 18". If you lower the board down even lower and cleat it at the second mark you will have a “full board” or about 28” of draft.
NEVER let the board down more than the second mark for a full board setting, as it will likely chatter or wobble in the trunk, and it is also not the best angle for the board in terms of performance. Occasionally though the board will still “chatter”. Lots of centerboards do. Usually it is a sign you are going quite fast, which is good, but if the noise or vibration is annoying, just pull the board up a tiny bit and the chatter will usually go away.
So long as you are within the limits of the recommended maximum depth setting, you can sail the Melonseed with the board set at any depth you like or feel necessary based on the depth of water you are sailing in. Note that the boat will not go to windward as quite as well with a half board or less as it will with the full board (set at the 22” mark) down. You need very little board down when running down wind, so if you want to fine tune the performance you can pull the board mostly or even all the way up. Be sure to lower it again before you tack or gybe, because it is very difficult to perform either maneuver without some board down. It you are going down wind in a very strong breeze you should absolutely have some or all of your board down for increased control.
If you set the boat down on a beach with course sand or clamshells you should ALWAYS check to see that something hasn’t become stuck up in the trunk and jammed the centerboard so that it will not fall down. Just before you set sail, give the pennant a little up and down pull to reassure yourself that the board is free to drop.
If you sail in a tidal salt marsh and there is a lot of marsh grass floating around in the water, or there is lots of floating seaweed, your pennant may collect bits of this flotsam and jamb it up inside the trunk. This is unlikely to happen suddenly, but rather over the course of a long period of time. If this happens and the board becomes jammed or does not go all the way back up into the trunk, then you will have to lower it down and dig the grass out with a stick. You will be amazed at how much eel grass can be compacted up there.
When you remove the bolt that holds the c/b in the boat you will find
that there is really a piece of PVC pipe that is holding the board in
place. It is like a bushing around the bolt so that the threads of the
bolt don’t wear on the c/b and there is a tight watertight seal.
Note the orientation of the bushing when you remove it, and when you
install it back in trunk with the new board put it back the same exact
Clean off the old sealer (3m #5200 or Sikaflex #291) from the old
washers and trunk. Lay down a big patch of masking tape over hole in
trunk. Punch hole in the tape big enough to dry fit the pin and
washers, and trace around the rubber washer to locate area that sealer
make contact with the trunk. With a razor knife, cut out circle or tape
that is under washer and sealer, leaving area around it all masked off
so the goop doesn’t GO EVERYWHERE! Apply modest amount of sealer on
trunk and rubber washer.
Tighten up bolt and nut just a little more than “hand tight”, not too
tight. Wipe off excess sealer and clean up bolt and then remove the
tape and things will be really neat.
Small Puffs of Wind Yield Large Gains.
When a boat has a properly balanced helm (called "weather helm"), she will naturally head up closer into the wind as it's strength increases. This behavior is particularly noticeable when a puff of wind hits your Melonseed. It's a safety feature that automatically points you up into the wind, luffing and letting the force of the wind slip by the sail.
Although already very close winded in her behavior, here's a technique you can use to sail your Melonseed even closer, quicker and faster to your upwind destination.
As you sense the wind increase, it's power filling the sail and heeling the boat over (this is called "getting a lift), keep the sheet tight or haul it in even more as you gradually point the boat more upwind. You must be aware of just how far you can turn upwind before you start to luff and stall the boat, but you'll be surprised at your new (temporary) heading. Most puffs of wind only last a few seconds though, after which the wind will lessen and often shift back. As soon as you feel the wind start to decrease, immediately turn the boat back off the wind a bit or you might stall losing momentum and speed. Done in a smooth "carving" motion both up into and back off the wind, it's a pleasant and efficient maneuver.
In spite of the fact that only a few seconds later you are back on the old heading again, you'll find that you have "side stepped" significantly more upwind. All good racers employ this trick. Doing this repeatedly on an upwind course will make a huge difference in time to your destination.
In general and when sailing downwind in most boats (usually they are Marconi rigged) the skipper’s eye is focused on the boom and keeping it far enough out downwind to prevent a gybe. Actually of course it’s not the boom, but the leech of the sail that gets caught by the wind, back winded, and thus causing an unwanted gybe. Folks tend to watch the boom though. Often there’s standing rigging (stays) that prevent the boom from going as far forward as one might like and that adds to the drama.
Things are different though with a sail rig featuring a quadrilateral sail. Sprit rigs, gaff rigs, lug rigs and many others are in this category. You must first understand that when sailing downwind in a sprit rig in strong winds that no matter where the boom is set, the peak of the sail will be much further ahead. There is a lot of wind force up there on the peak of the sail, and so long as THAT part of the sail is not at serious risk of gibing, then what’s going with the boom and the lower part of the sail is of less concern than you might imagine. There is often so much “twist” in the shape of the sail that when going downwind in a strong breeze the peak of the sail can be 18” – 24” ahead of the clew back at the end of the boom! So here’s the deal…it’s neither the peak nor the clew that needs to be at the optimum angle to the centerline of the boat (about 90 degrees), but HALF WAY UP THE LEECH OF THE SAIL. Therefore if you keep your boom BACK about 9 – 12” from perpendicular to the C/L it will set the sail just right. There is a lot of force on the peak which is a foot or so ahead of perpendicular, and that will keep the sail from gybing.
WHAT NOT TO DO: OK, so you are going like hell downwind in a heavy breeze in the Melonseed and it starts to feel a little scary, so you instinctively let the boom and sail out thinking that letting air slip off the sail it will ease things up a bit. Perhaps you are also worried about the “killer gybe” scenario as well so you see this as a preventative measure. The result of this is that you may now you may have the boom perpendicular to, or perhaps even worse, well ahead of the mast.
When the boom is out ahead of the mast the sheet no longer has the ability to “vang” (hold or pull) the boom down and the boom may start to lift upwards. This can turn into a pretty awkward situation in any cat rigged boat, not just the Melonseed. The boom might suddenly rise WAY up in the air and this will turn the sail into a weird crab-clawed shaped spinnaker with the center of effort of the sail now located much higher and further ahead of the mathematical location it needs to be for the boat to behave right. The boat may start to roll side to side and get very strange to handle. Well, if a boat ever does this and it has a free standing swiveling mast like the Melonseed then just simply let the sheet go and the drama will cease. Better yet, if you see that this is starting to happen, then just turn the boat a bit from a dead run to a broad reach (not by gybing of course, but an “upwind” turn) and keep the sail trim the same or even ease it a bit. Your might even go a bit faster trimmed like this, but you will certainly have a lot more control of the boat.
We all know that raising the centerboard on a boat when going downwind will allow the boat to go faster due to having created less “wetted surface” and less drag. That’s fine in most wind conditions, but I feel strongly that in the Melonseed it’s important to have at least some centerboard down when the wind gets strong. It’s OK to have a normal full board down as well. You will have better control of the boat. And too, if you working harder than normal to keep all things going right with the tiller and sheet and you suddenly have to tack or gybe, you will need to have the board down. Lowering the board in a moment of crisis is not what you want to be doing. Plan ahead, be in control and leave yourself more options.