Building a new daggerboard

I’m need to make a new daggerboard and rudder for my Dolphin Sr. I wanted to run my plan by someone to make sure I’m not about to make another mistake.

My plan is to glue together multiple 2”x2”x4’ strips of clear grain western red cedar with a 2”x2” strip of white oak on the outside edge of the cedar.

I’ll have it planed down to 1 1/8” thick and hand shape it to a 1” thick “NACA 0009” shaped foil. Drill holes to hold the pins that will keep the daggerboard from dropping through the trunk.

Then I’ll cover it in 10oz fiberglass cloth and epoxy.

I’ll repeat the process for the rudder, minus the pin holes.

Any suggestions or problems I’m missing?

Thank you in advance!

 

My first suggestion would be to strive for a bit more accuracy in aligning the strips when gluing the blank.Then you won't need to turn half of the raw material into shavings before beginning the project you are really interested in.If you can get hold of a cheap biscuiter or a biscuiting cutter for a router,it ought to be possible to use strips no more than 1/8* thicker than the blank needs to be.I think you may be surprised by the sheer quantity of shavings you will produce in the shaping process.do you have prior experience in creating accurate foil sections?

 

I had planned on using dowels and while I say 2”, it’s actually 1 3/4”. So I won’t be taking off that much. And this is the first time I’ve ever done this, so I will be using templates to guide the shaping process.

 

Your plan looks good to me! Just don’t skip the shaping stage that foil shape really makes a difference under sail. Flat boards create a lot more drag.

 

I would spline the pieces together. All the work is done on the tablesaw, and you get more quality glue surface. The alignment should be as good or better than dowels. Use finger boards.

-Will

 

I didn't and wouldn't recommend the process,mostly because here in the UK it has been a long time since it was permissible for professionals to use a saw without a crown guard and riving knife.If they are mandatory for professionals,I don't encourage amateurs to avoid their use.The use of splines is a good way to align boards and I have a few router cutters that can do it well.A solid blank is a great starting point for a nice foil and I totally agree that they are much better than a less sophisticated alternative.A keen amateur is more likely to be diligent enough to accurately produce a section template and to make it fit precisely,and then to reap the rewards of the work that few professionals could dream of charging for.the sheathing is a miserable job,but does add to the longevity and toughness of the new foil.The difficult part is to arrive at a fine trailing edge.

 

You can't cut dados with those safety features in place? Anyhow, if it is a professional shop, a router or a shaper table should perform the same function.

A lot of shops here in the States, esp. school shops, have installed the SawStop safety system.


-Will

 

If you use the proper glueing presser when clamping you will not need any biscuit, splines, T&G...
Glueing instruction for PVA titebound
Dale Zimmerman of Franklin International, maker of Titebond woodworking glues, recommends 100 to 150 pounds per square inch (psi) for clamping softwoods and 175–250 psi for hardwoods.
Resorcinol 100 -l 250 psi to achieve optimal bond strength. Some sources mention a slightly lower range of 100-200 psi for some types of resorcinol glue.
A three-quarter inch bar clamp can typically exert a clamping force of 1,000 pounds. A hand bar clamp is less than 100 pounds.
If you are covering it in 10oz fiberglass cloth and epoxy that will hold it all together and if you use epoxy glue it will need less presser in glueing it together.

 

Some good points there about gluing,but if you are planning to glass sheathe,all the glue needs to do is hold the wood in place while shaping the blank.Once the glass is in place it has so much more strength than the wood that the sheathing alone will hold things together.I hope the OP has made his templates to allow for the thickness of the glass.I allow around 0.3mm for 180gsm glass cloth and resin.One of the benefits of modern times is that it takes little effort to find foil offsets and to use a computer to create the sections,and then to offset the shape for sheathing and then printing out the result-or if one has the connections,getting the templates CNC cut.I don't believe anybody who has ever sailed with good foils would ever willingly revert to anything less efficient.

 

I reshaped one of my sunfish's daggerboard and rudder that has a parallel mid-body PMB section. Reshaping the leading edge to more of a 3/1 Ellipse LE the best I could and didn't do anything to the Trailing Edge TE. Leaving the PMB section the same so it would fit in the daggerboard slot without banging around when I would adjust it up to run down wind. I couldn't tell any difference in than boat performance than my other Sunfish with the standard daggerboard and rudder.
Learning to read the winds puffs as well a good roll and tack and when to ducking behind my opponent has given me more of an advantage than modification my boat. Most sailor who sail on lakes have a good chance of understand a puffs shift than those that sail in steady air.

 

Perhaps the perfect illustration that a better leading edge can't get away from a sub-optimal trailing edge?

 

I won’t! That’s the reason I’m making it myself. I could just buy a used daggerboard but it wouldn’t be what I want. Thank you!

 

I actually have a router with a bit to do finger joints and I may actually do that instead of dowels. Thank you!

 

I will probably use a router and a finger joint bit to join the piece. While I do have the guard and riving knife, I think the router would be best. And as for a solid blank, I had thought about that but it would be more expensive and heavier. I want the weight of a cedar core and the strength of a white oak edge. I’m tempted to use live oak or post oak but they are hard on tools. Thank you!

 

Thank you!! This hadn’t occurred to me before. I’ll make a jig to apply even pressure across the entire length of the blank. I’m not sure how I’ll be able to measure the pressure though. Thank you for the advice!