An Ilur in Hansville

[Michael_Owen]

Cool. I found that exact sizes of the little stand thingies was not crucial. I ended up sliding them around a lot. May have even replaced some of them with sticks.
I did use a laser along the side to make sure the mast was straight. I did a lot of dry runs before gluing. This helps with the plugs and stuff, too.

mast set-up.jpg

laser.jpg

laser pan,.jpg

In the last two pix you can just make out the laser line

[davidladd]

ilur 045.jpgilur 046.jpg

I'm stuck. I have all the staves scarfs epoxied together and the mast head/sheave fabrication, and the mast step plug roughed out, but I have questions I am hoping someone can answer. Before I measure and cut the staves for the mast taper I want to confirm what the formula is for determining that measurement. Geoff Kerr's video on Off Center Harbor said to multiply the overall diamater of the mast at a particular station by .4. But when I looked at other YouTube sites they said to use .2.

Before I finish the mast head/sheave fabrication I want to know about how to determine the mast head sheave height. The plan I have doesn't give a height, but by measuring the drawing it indicates that it is 5.5" below the mast top. However, that drawing is also used for a rig that has a fore sail and has a hole in the top of the mast for that. Since my rig is a balanced lug and does not have a fore sail, can the mast head sheave be placed higher up the mast? How high can I go without jepardizing the strength of the mast at the top?

When making the mast step plug, how important is it to cut a weep hole in the center of the plug. The mast step plug has a kerf for drainage, but I don't see a drain hole in other peoples mast step plugs.

[pvg]

https://www.duckworksmagazine.com/10/howto/birdsmouth/
Be sure to use the formulas for how you cut the bird's mouth (centered on the edge, not offset). Take some time studying this stuff; there's a lot there, but in the end it's simple.
pvg

[davidladd]

Thanks pvg,
I checked out that site. It has a lot of info. It looks like it gives you dimensions for a mast that is just one size OD. I didn’t see any formula that tells me what the L dimension is for tapering the staves. Geoff Kerr’s video says to multiply the OD of the finished mast at a specific taper point by .4 and that is the L dimensions for the individual stave. I was hoping to verify that.

[davidladd]

Pvg, I finally figured out how to use the formulas. Thanks!

[pvg]

I also left the individual strips straight along the top and bottom for about the length of the plugs; this way the plugs don't need to be tapered- which would be a bit more difficult than a simple straight octogon plug.
Since the mast will therefore be solid at the ends, the tapers there can be done from the outside after glue-up.
pvg

[stromborg]

I taper the staves before glue-up. I lay the staves on the bench with the "vee" down, all clamped together in one block. Using the online calculators to find "L" I rip a matching taper into two pieces of wood long enough to lay along either side of the mass of staves and use that as a guide to plane them down to thickness all at the same time. Think of it as a modified scarfing sled.

[stromborg]

I don't think you can get your masthead sheave "too high" unless it starts to interfere with something going on above.

[pvg]

I taper the staves before glue-up. I lay the staves on the bench with the "vee" down, all clamped together in one block. Using the online calculators to find "L" I rip a matching taper into two pieces of wood long enough to lay along either side of the mass of staves and use that as a guide to plane them down to thickness all at the same time. Think of it as a modified scarfing sled.

Yes, tapering the staves before glue-up is necessary to keep the wall thickness uniform; otherwise the walls become thinner the more you taper. But as I mentioned, I only taper the plugged ends- which are now solid, not hollow- after glue-up. Makes fitting the plugs easier.
I had expected to have access to a nice long, flat "spar bench"; but CV got in the way. So I had to "freehand" the task; took longer and was a bit more tedious, but worked out ok...
pvg

[davidladd]

Thanks to each of you for all the input and info. I am taking it slow with measuring the taper on each stave. I’m nervous about making a mistake and then planing the staves down to far. I like the idea of making a taper template for each side of the ganged up staves to use as a guide. In the mean time I’m I’m still working out the plan for the mast head/sheave fabrication. I will place the sheave higher than I had originally though based on input. I am also going to use some 1/8” G10 sheet instead of plywood as cheek inserts where the sheave will ride against. After talking with Clint Chase I won’t be making a mast step tapered end for the mast foot, but instead will just insert a Doug fir plug which I still have to make once I start to dry fit the staves. This is going to be a long process for me, but that’s ok. It’s now time to learn how to use a hand plane and a power plane.

[Pete Bergquist]

I would recommend some practice with the power plane David. Learn how things can go wrong. With the PP, when things go bad, they go bad in a hurry. It's a great tool once you have the hang of it - it just takes a little time.

[WI-Tom]

I set my power plane to take off the barest little shavings when I started with it. Much easier to take more off than put it back on...

That said, I didn't have any problems. Used it for my spars, keel, stem, probably more. A truly handy tool.

Tom

[davidladd]

I keep sneaking up on this hollow mast. I spent some more time making and changing some alignment blocks, did my first dry fit, and make the mast step plug. I also changed my mind about the mast head/sheave fabrication. After talking to Clint Chase I ordered some 1/8" thick G10 to use as inserts in the cheeks instead of plywood. My 60mm sheave came in so until the G10 comes in have no more excuses. I'll start working on tapering the staves. I'll try roughing them down with the table saw and see if I can handle that. If not I'll start with the power plane then go to the hand plane.

One thing I haven't heard anyone talk about is what to do about he interior of the mast staves. Do you just leave them unfinished or would you recommend putting on a coat of epoxy, or two?

[Powerwagon]

Looking good!

[Clinton B Chase]

I would recommend some practice with the power plane David. Learn how things can go wrong. With the PP, when things go bad, they go bad in a hurry. It's a great tool once you have the hang of it - it just takes a little time.

Boy is that ever the truth. The smaller the plane the better...my small Bosch PP has earned me some income when I farmed myself out "back in the day".

I do most of my shaping with a bench plane and a block plane. Take off the corners to make it 8 sided > then mark out for 16 sides > plane to those lines to get 16-sided > then block plane by hand and eye until it is effectively round. Only then switch to sandpaper using a box sander to go with the grain. Many new boatbuilders make the mistake of switching to sand paper too soon and not using a course enough paper when you do. I would start with 40 or 60 grit and work up to 120.

[davidladd]

Hi Mike,
I’m really close to glue up of the main mast but I have a question. After you made the mast head/sheave fabrication, did you shorten the top of the mast to the length of the fabrication so the final mast length is correct?

[davidladd]

The mast is now tapered and ready to go. I wasn't happy with my mast head/sheave fabrication so I'm making another one. Instead of using plywood inserts in the block side cheeks I'm using 1/8" G10. It is a very stiff material and because It is only 1/8" thick it doesn't remove as much cheek material. As per Clint Chase I'll over drill the 5/16" rod hole and fill with Gel magic and then redrill for the sheave rod.

The protruding part of the mast head fab is 6". Can anyone who has done this tell me if I need to cut off the top of the mast 6'' so when the mast head fab is inserted the mast length is correct. Or do you just insert the mast head fab and increase the mast length by 6"?

[Michael_Owen]

You could cut some material from the top. I might just leave it, though. You could ask Vivier. Maybe split the diff. and cut 3".

My feeling is that a few inches more height will give you a bit more clearance on deck, especially with the full sail (no reef.) You can always adjust the halliard down if you feel like it.

On my Whilly Boat, I made the mast a couple of inches too short and I regretted it. Sail sweeping the deck/crew.

Mike

[stromborg]

I don't have any personal experience with the Ilur so take this with a grain of salt. There are a number of nicely sorted Ilurs floating around, I don't remember hearing anybody complain about the mast being too short. On the other hand just looking at the designer drawings above there doesn't seem to be much room up at the top, I'd be inclined to leave the extra 6", the leads for your rigging will be a little better and there will be more "wiggle room" for your hardware to sort itself out. The downside is storing the mast but I think this one is longer than the hull anyway, right?

[John hartmann]

I agree with Mike and Steve. Plans call for 5.1 m, about 16’ 8”; WaxWing’s mast is 17’ 2”, and I like it well:

F511DDB8-7981-47FE-A887-D26210310787.jpg

[davidladd]

I finally have the birdsmouth mast, step plug, and mast head/sheave plug done and I'm ready to epoxy it up tomorrow. I've done lots of dry fits and have all the hose clamps laid out and ready to go. The only unkown for me is the thickened epoxy mix up. I'll start with a batch and count how many scoops of thickener is use so the next batches will be the same.

[stromborg]

You are on the right track. Best of luck with the big glue up tomorrow

[Clinton B Chase]

Do you have more clamps David?

Looks good, best of luck!

[davidladd]

The glue up is done. I had a good friend (Shelly) help me and I don't think I could have done it by myself. It was good to have a person spreading the epoxy while I mixed up another batch. I had bought 20 clamps (two at each end, and the rest about a foot apart). So that is what I clamped up with. After it was all done I went in for lunch and saw Clint"s post about having more clamps. I found 8 more old clamps that I had and then i used some zip ties. Of course when I was pulling hard on the zip tie the pliers slipped and hit my head. I knew it wasn't good when I started to feel liquid running onto my glasses. But, It wasn't that bad and after putting on a band-aid i went down to my local Henry's and got 10 more clamps. Not sure if it was too late to put them on but i did any way. I ended up with 38 clamps. Tomorrow I might take a day off. This hollow mast has taken about two weeks so far and I still have to taper the step end, make it round, and shape the step tendon.

[davidladd]

The mast is planed down to 32 sides and ready for some sanding. This was the first time i used an electric power planer. It worked great. I kept it at a minimal removal setting and just made multiple passes. Then I finished it down to 32 sides with a block plane. I really love my Lie-Nielson block plane. After I sand the mast round I'll work on tapering the step end and then cutting in the mast step tendon.

[WI-Tom]

Looks great! Power planers are the bomb diggity; my DeWalt is the nicest tool I own.

Tom

[jpatrick]

David you owe it to yourself to read up on the toxicity issues of epoxy. It hardens quickly but takes longer to cure and fully off-gas. I wait a few days before milling to the extent that you have done on the mast.

Otherwise, it is looking great.

Jeff

[davidladd]

Thanks Jeff, it’s always good to be mindful of toxic materials.

[davidladd]

Finally, the main mast is 95% done. Its been sanded to 220 and the base step tendon has been fitted. There are still some scratches in the mast surface caused by the block plane hitting some back grain. I am figuring that out. There are just a few places where my fingers can feel a slight flat spot, but you can't see them and I think I'm done. I strive for perfection but usually get around 75%. As long as its functional I'll be happy.
What I don't know is just how I'll finish the mast. I like the idea of painting the top 2' white and I'll probably paint the bottom 12" white. I think I'll go with Deks 1 & 2 between the ends. What I don't know yet is just how to finish that base step tendon and what the fit is between the base tendon and the mast step, and how to determine how to get a good fit when I'm done with what ever finish i put on it. I'll epoxy the mast step. Should the mast base tendon be epoxied, painted, or Deks'd? Anyone want to add some advice?

[Gruds]

Good job on the mast but it is a tenon at the bottom, not a tendon.

[jpatrick]

I epoxy coated the tenon on my mast step to help manage water absorption in order to keep it from swelling. This seems to have worked, mostly. Some years I have to wiggle the mast a bit more than others when I unstep it at season's end.

An accompanying feature will be a wedge to keep the mast properly located in its step. I first used a wedge made of hardwood but always had trouble getting it out after swelling. I now use one made of UHMW which doesn't absorb water at all but since it's so slippery it must be tied into position.

And now, thinking about it... perhaps I ought to make a new tenon out of the UHMW also. My step tenon is not an extension of the mast wood. It is screwed on.

Jeff

[davidladd]

Thanks Jeff, it’s good hearing from others what works and what doesn’t work. It’s hard to make decisions when I have no experience or knowledge of what I’m doing.

[davidladd]

Thanks Jeff, it’s good hearing from others what works and what doesn’t work. It’s hard to make decisions when I have no experience or knowledge of what I’m doing.

[davidladd]

I decided to put the main mast away for now and wait for better weather before painting, and Deks'ing. The humidity is high and it would be better if it was hotter for the Deks to soak in. I made a mast rack for storage. I don't have the material yet for the yard and boom so the next step is to scarf the NC joints in the planks. If I do 4 planks a day it will take 5 days to get all 20 done. It doesn't take much time to clean up the scarfs and get them epoxied so I'll look for something else to fill the day. I'm sure there is some clean up or other aspect I can work on.

[davidladd]

I am still so glad I am doing my first boat build with a kit. It would take me forever to build from scratch. But even with a kit there is still a lot to do. Everything comes is 8 foot sections and there are many scarfs to do. I have two days left the scarf the rest of the planks together. With the NC scarf joint that Clint Chase provides it is pretty easy. So far all the scarf joints have been tight except for the shear plank. There was just a little play, but it doesn't take much play at the joint to effect the ends of the plank. To make sure the plank is epoxied to the right shape Clint provided the plank offsets. To check the off set I weighted down the planks and then stretched a string from tip to tip on the inside curve. Then I measured the distance from the string to the plank. After a minor adjustment I placed some brads next to the plank to mark its correct shape and also marked the plank location on the strongback. Even with a tight scarf fit it is easy to check the offset.