Bladerider Foil Mods

I’d like to get a new set of foils for MB1, but I can’t quite justify that expense at the moment.  That being the case I looked at my current foil package to see if I could modify it to improve the overall performance.  I’m currently running a home-built front foil designed by Gui and a Bladerider rudder foil.   I’ve considered cutting the tips of Gui’s foil, but I’m not going to go there quite yet.  That leaves the Bladerider rudder. It’s clear that the current trend is for symmetrical rudder foils and the stock Bladerider foil is far from symmetrical.  I looked at the foil shape and decided that it should be possible to make the foil more symmetrical by modifying the trailing edge.  Below is a typical NACA section that is pretty similar to the Bladerider rudder foil.  This foil really has a lot of ‘flap’ which can’t be very fast for high-speed sailing and probably produces a lot of drag at all speeds.  The red line shows what kind of section you’d end up with if you removed part of the trailing edge.  

 

This section looked quite a bit better to my eye so after a bit of checking to see how much carbon was in the trailing edge of the foil I simply took a large file and removed about 3mm of the trailing edge.  Then I thinned the bottom side of the edge to remove more of the ‘flap’ and repainted it.  What I was left with was a foil that still isn’t symmetrical by any means, but it is far more symmetrical than it used to be.

So far I’m really happy with the performance.  It may not have quite as much low-speed lift, but also seems to have less drag.  The largest benefit I’ve seen so far is that I don’t need to adjust the pitch of the rudder as much when going from an upwind mode to a downwind mode.  Previously it felt like I needed to decrease the pitch on the rudder when going downwind to keep the boat from getting uncomfortably nose-down and then increasing the pitch again when I turned upwind.  Now the boat feels much more stable in pitch on all points of sail.   It also seems like the foil is less prone to cavitation.  So should you take your stock Bladerider foil into the shop and grind it down?  I’m not going to go that far yet, it could turn out that grinding this much off the trailing edge weakens the foil, but I do think it improves the overall performance.  So if you have an old Bladerider foil laying around that you don’t mind breaking, it’s may be worth the 30 min it takes to modify it.

Pimp My Moth

Decided to bring some bling to my moth experience by upgrading my ride. I'm talk'n Cadillac Escalade yo!   And chech out the cute young thing at the wheel.  Don't be hate'n when I pull up in this bad boy at the next moth event.  Peace.

It's Alive!!

For all of you that have been wondering what the fate of Mothball 1 was, well here she is, fully repaired and sporting new tramps.  The repair of Mothball 1 was actually fairly easy.  After cutting out all of the crushed plywood I just made some new plywood backing plates and epoxied them in place, then re-attached the mast stump and cut more plywood to fill in the gap.  To make sure it never fails there again I reinforced the whole area with carbon and then added a forward facing compression strut (as suggested by Phil) to take the forward loading from the mast.  When I was designing the boat I never really imagined the amount of forward pressure at the mast stump from the vang so I'm not really surprised that it failed there.  All in all I’m pretty happy with the repair.  I took the boat out to do a shakedown cruise yesterday and everything worked well.  Now I need to do a few extra mods and repairs that I forgot about from last summer and I should be ready for the season.  Maybe my next project should be a new dolly?

Dude, where’s my stump?

 I was planning to show you guys the photos of all the cool improvements I’ve made this year.  Ride-height adjustor, new gantry, stuff like that, but now I have a new moth chronicle to relate.  I went out sailing early this morning because the forecast was 10-15 diminishing by noon.  I rigged up the boat and it looked like it was starting to blow pretty good on the water.  I was ready to try and get some good numbers on the GPS.  I headed out and started sailing downwind.  The wind was a bit puffy and I instantly was sailing 15-18 kts with good control.  As I made it down the lake farther the wind started to pick up more.  I sailed down the lake for about a mile and then came back up to meet some family members who where sailing my way on keelboat.   I pasted them going upwind and then bore away again in a big puff.  This one was really strong.  The GPS log put me at 20+ knots for over 60 seconds with a max speed of 23 kts, my new personal best.  The boat handled fairly good but I decided to work my way back upwind in the big breeze.  Upwind was pretty hard, by now it was blowing 25-30 steady and I was having a hard time getting the boat going into the stiff breeze.  I sailed back to the marina and took a break hoping the wind would settle a bit.  About an hour later I headed back out.  The breeze was down a bit, but pretty steady around 20 with some good waves.  I was sailing downwind at about 18 kts and stuffed the bow into a wave, it didn’t seem like a bad impact but the terrible crunching sound told a different story.   The boat flipped over and I instantly knew something was very wrong.  I righted the boat but the rig was clearly down.  Looking forward the reason became instantly clear.  The mast stump was completely gone, just a jagged hole remained in the top of the boat.  The rack struts just hung in space.  I wasn’t too far from shore and the wind was blowing me that way so I wasn’t too worried about being stuck in the lake.  I swam the boat toward shore and watched helplessly as the mast which was now bouncing in the waves on the unsupported racks breaking the joints.  It took some effort to keep the gaping hole on the top of the boat from taking on water and filling the forward tank.  Finely I got to shore and started taking the boat apart.  Shortly after my family came along looking for me and we stacked all the broken parts on the deck and started back to the marina.

After taking everything apart and looking at the broken bits I’m happy to say that Mothball 1 will sail again, but not this season.  The racks should be easy to fix and there wasn’t much other damage.  Thankfully I didn’t lose anything.  The remains of the mast stump were held to the boat by a small guide and the tiny line for the ride-height adjustor.  The stump had failed by compressing forward into the deck.  I should be able rebuild it and reinforce the area to take the massive loads that I’m starting to put on the boat.   All in all it was a good day.  I’m just glad I didn’t get hurt or sink, but mothing season 2012 is now over :(

Time for an Upate

Where has MB1 been this summer?  Well sailing actually.  So far this year I've logged over 100 miles on the foils.  The boat is working great and I'm starting to feel pretty confortable at the helm.  My tacks and jibes still have a long way to go, but I'm pretty sure that I could race the boat now and not make a fool of myself.  I'll post some more info about the mods I've made this year over the next few days. 

As a moth sailor all I can say about the flying AC72s is Fuc$ Ya!

Stainless, Brass, or Carbon?

I’m in the process of building a new gantry out of carbon.  It looks really good (pics soon), but I’m planning on upgrading my rudder pin in the process.  Right now I’m using a ¼” stainless pin which has worked fairly well, but I’ve bent it several times so I don’t think it’s really up to the task.  For a replacement my choices are 5/16” stainless, brass, or carbon rod.  Stainless is the most obvious choice but it seems like brass may work just as well and is far easier to work with. My other choice is a solid carbon rod which would be way lighter than the metal rods but I’m not sure if it would be up to the task.  Carbon would also be able to flex without bending and could shear off without damaging the rudder.  Any advice?

Space Moth

I was looking at Google Earth yesterday and realized that the satelite photo of my area had been updated.  It was clearly a summer photo and the lake was busy so it must have been taken on a weekend.  After a bit of searching I found Mothball 1, unfortunately I wasn't sailing.  The boat was under its cover in the rigging area, so I must have been getting ready to sail.  Can you find Mothball 1?

Upward Force

I have a new question for all you Mothies out there. How much force does it take to hold the daggerboard down while sailing? I’d think that there must be quite a bit of force upward on the daggerboard while sailing between the weight of the boat crew and acceleration forces. The reason I’m asking this is because I need to re-design my daggerboard box to work with my ride height adjuster. The daggerboard box on Mothball 1 is a 1”x 8” rectangular reinforced box that has a tight insert that bolts into the daggerboard box at the top to kept the foil from raising above the deck level. Then I had a pin that mostly kept the daggerboard from falling out while sailing. However, I need to change some of these parts to make the ride-height adjuster work and that includes cutting off parts of the daggerboard box insert and many of the areas that bolt the insert to the boat. Clearly I need a major re-design here. So the questions remains, what’s the best way to hold the daggerboard down? The two best options I see are to simply beef up where the pin goes through the daggerboard and assume that it will hold up. But my other idea is a bit different and seems like it would be much stronger. The other ideas is to bolt a removable flare onto the daggerboard at the bottom of the hull, so instead of holding the daggerboard down from the top with a pin, the flare would push up on the bottom of the daggerboard box in an inset receiver and prevent the foil from moving, then I’d just pin it on the top again to keep it from falling out. I kind of like the flare idea because I could make the foil/hull interface much stronger and stiffer utilizing the beefy rectangular daggerboard box originally designed in the boat. How do other boats deal with this?

Boat-Work Season

It’s still a bit cold to begin sailing in Montana, but ski season is officially over so let boat-work season begin! Thankfully most of my projects this year will be easy, I want to re-finish pretty much everything and make a few mods/improvements, but nothing too drastic. One of my projects for this year will be to construct a new rudder gantry. I must say that the original gantry that I fabricated out of solid oak was probably the strongest thing on the entire boat. After two years of useit never had a single failure, but that’s probably because it weighs a ton. Going to a carbon gantry will save me a lot of weight. So now I’m trying to figure out what diameter and wall thickness I need in a carbon tube to give me good weight savings but still be reliable. Is there a standard recommended size for gantry tubes?

2012 Projects

Now that Mothball 1 is stripped down for the season I’m starting to think about improvements and mods for 2012. Some of the modifications I’ve already started. Let’s start with foils. After checking out the information on Bruce McLeod’s blog (http://www.teknologika.com/mothblog/the-evolution-of-moth-main-hydrofoils/) I concluded that my main foil was too big. It was about 10% larger than the Bladerider main foil. Enter Mr. Dremel. After inspecting the foil and comparing it to all of the other foils out there I decided that my flap was too large, in particular at the tips. I couldn’t take too much off the flap, but I did taper it down 10mm at the tips. This should bring the flap into better proportion with the cross-section of the rest of the foil and reduce drag. Tapering the flap reduced the total area by 5%. I’m considering cutting the tips down a bit to reduce the area even more, but I may wait a bit for that. Does anyone know the approximate area of the M2 foils?

I’ve also decided that I want a ride-height adjuster. I can get good height, but it seems like I always have more height sailing downwind. If I set the height for downwind then I’m a bit low upwind, and if I set it good for upwind then downwind is horrifying. Is this normal? I saw the ride height adjuster on Sailingbits.com (http://www.sailingbits.com/catalog/moth-ride-height--gearing-adjuster-p-377.html). Does anyone know if this adjuster will fit onto Bladerider components? Seems like buying one of these would be way easier than developing my own system.

These are my only two big planned changes. I want to refinish the hull and make some other minor repairs, but these are relatively easy. My hope for 2012 is to get things sorted and then make it to some Moth events on the west coast.

End of the Road

This weekend was the last mothing in Montana, and a beautiful weekend it was. The breeze was a bit variable, but I did get a few good sessions. My last sail was in 7-10 kts of breeze and I logged 14 miles in 1.5 hours at an average speed of about 10 kts. I also pulled off four fully jibes and didn’t ever get the sail wet. I’m to the point I’d feel pretty comfortable taking Mothball 1 somewhere to race and I don’t even think I’d embarrass myself. But for now it’s time to start thinking snow (forecasted for Friday). Mothball one will be fully stripped down and prepared for a full refinishing next spring. I have some ideas for mods and new parts, but I’ll save that for another day.

A Day of Many Firsts

I had a lot of new and different experiences today on Mothball one, some of the experiences were good, others not so much, but I ended the day with a smile. I went out this afternoon with 8-10 kts of breeze and quickly had my first new mothing adventure of the day. I was sailing towards the shore and knew there was a shallow spot somewhere. I was about to turn when I looked down and saw the bottom way too close. I quickly thought about whether it would be better to keep foiling and pray that I make it over the shallow spot or just eject and hope for the best, but about one second later the decision was made for me as the boat hit the ground and I was shot into the water. I stood up in the thigh deep water and was feeling pretty stupid, but after some inspection I realized that the damage was fairly minimal, just some scratched paint and a small crack at the end of the daggerboard box. Lucky. The wind was still nice so I just swam out to deeper water and took off again and kept sailing for another hour.

The wind started to die so I went in to take a break. The wind was forecast to come up later in the afternoon so I stuck around to wait for it. It took some time, but the wind finely came up late in the day. I sailed upwind with some good pace into the building breeze. The wind was blowing down the entire 30 mile length of Canyon Ferry Lake and with the wind increasing to 15 kts the waves started building quickly. I sailed upwind for about three miles and then turned around with the wind still increasing. By the time I was heading back down the lake the wind was gusting to 20-25 kts and the waves were getting quite big. This was the first time I’d ever sailed downwind in big waves. I hit a max speed of 19kts in the lumpy seas even with my scratched main foil. After launching over a big wave I did my first high-speed ventilation of the main foil and crashed rather dramatically. I crashed several more time before I figured out how to drive the waves to avoid the big breakers.

As I was getting back to the marina the wind had decreased to around 15 and the seas had flattened quite a bit. I had to make three jibes to make it back to the docks and I was hopeful that I could end this exciting sail with a foiling jibe. I went into the first jibe feeling good and the boat stayed flat and fast. I got to the other side in position and sheeted in and kept sailing. Yay! First foiling jibe = DONE! My next jibe didn’t go quite and well, but I was able to stay up on the last jibe too.

So it was quite an exciting day on many levels. I tried to ruin my boat, but didn’t, I sailed in big waves and survived, and I made two foiling jibes. Too bad this sailing season is almost over, this is getting fun!

20 Knot Barrier = Broken!

I know that doing 20 kts on a moth is really nothing special, but breaking 20 kts on homebuild with homemade foils is still pretty cool in my book. I went out tonight expecting to a 10-15 kt breeze but was pleasantly surprised with a 10-20 kt breeze with some higher gusts. On two separate runs I recorded speeds on the GPS of over 20 kts with a max speed of 20.9 kts. The boat did very well, but I felt like I needed to change my pants afterwards. No matter how you cut it, 20 kts over the water is really fast. I can’t hardly imagine what 30 kts is like.

I’m getting closer to the illusive foiling gibe too. On two different attempts tonight I stayed flat and on the foils all the way through the jibe only to fall off at the very end due to not enough wind and speed. I’m not there yet, but I’m getting very close...

Cascading Failures

It’s amazing how small breakages can instantly get worse. I was out sailing last night in some nice 10-15 kt breeze and the boat was felling really good. I made a high-speed pass of the shoreline and suddenly BLAM the vang explodes. The boat goes instantly out of control and I spin and crash fairly violently. A quick look at the vang confirms that one of the small attachment lines has worn through and exploded. No big deal, I can re-tie it on the water and keep sailing. After fixing the vang I take off again but the rudder has a terrible vibration, something is clearly very wrong. I stop the boat and go back to check the rudder, everything looks ok, but on closer inspection I see that the rudder has split down the middle. You may remember that the daggerboard did the same thing to me last year but I was able to fix it and it hasn’t had any trouble since. But it’s strange how a simple broken line on the vang can cascade to a broken rudder. I’m really hoping that I’m running out of things on this boat that can break, but I shouldn’t be too surprised about failures as I start to push the boat harder. Thankfully this is another easy fix. Test, learn, improve.

I did find the cause of the mysterly leak too. There was a small crack in the chine below the hole that my brother put in the side with his head. Right now its fixed with a piece of tape. Yet another easy fix :)

Mystery Leak ?

Mothball One spent most of the day in the water on Saturday. It was a nice day but not much wind. I went out several times and chased some Fins around and let my brother take the boat out. The hull was in the water for about 8 hours and most of that time it was upright. When I took the boat out of the water and opened the drain plug I was greeted with a puff of air from the plug hole indicating that the hull was still sealed and pressurized. But then I started moving the hull around I heard water sloshing around. I tipped the boat up and got about a liter of water to drain out. So here's the mystery, how did I get water in a hull that appeared to still be sealed and pressurized when I took it out of the water? This is the first time I've ever gotten water from the hull after a day of sailing that I couldn't explain.

Wand Tension ?

I've been looking around for some insight on wand tension but I'm not having much luck. Specifically, how much wand tension should I be using for different wind conditions, upwind vs. downwind, flat water vs. waves. How much tension is too much/too little. Anyone have the answer to these questions?

More Broken Bits

I am truly amazed how many things you can break on a moth. I spent a lot of time on the water last weekend in a variety of conditions, everything from 5 to 25 kts. Thankfully nothing actually broke on the water. I was hoping to take Mothball 1 up to the Montana Cup this weekend so I broke everything down after sailing and inspected everything and made a list of repairs I wanted to make before trying to race the boat. Here it is:

1. Fix ripped grommets in the tramps

2. Reinforce vang mount

3. Reinforce forestay attachment

4. Repair rack joints

5. Replace mast rotation pin

6. Reinforce gantry attachments

7. fix wand tip

8. Modify spreader attachment

9. Fix rudder pintle holes

Luckily all of these are easy fixes. I'm hoping that I'm running out of parts that can break. Unfortunately I don't think I'm going to make the MT Cup afterall, but its nice to know that I'll be ready next time...

Video (Finely)

It took a few more days than I was expected to get this video, but I think it looks pretty good :) The video was taken from a moving boat so it looks a bit slow.

That's Using Your Head

Mothball one is look'n pretty good, despite some minor injuries. My brother Jeff was jones'n to take the boat for a spin on Saturday evening in some pretty good breeze. Unfortunately his ambition did not quite match the conditions and after accidentally letting the cunningham completely free and not noticing, the boat became pretty uncontrollable in the 20kt breeze. After crashing several times in a row he ended his ride by falling backwards off of the racks and landing head-first on the hull. It was a pretty violent fall and he hit hard enough to put a pretty good crack in the hull. Thankfully he wasn't hurt and after making a few rig adjustments I was able to sail the boat back to marina and I even got it on video (check back tomorrow). After fixing the boat with some sail tape (see above) I sailed some more this afternoon in a pretty nice 8-10 kt breeze. Thanks to Valerie for the pic and movies!

Broken Butterfly

Today was another good day for mothing. After dorking around in some light winds this morning the winds came up to a good 20-25 and Mothball One was put through her paces. For the most part the boat was handling the conditions pretty well and I went out several time and worked on upwind and downwind handling. Gybing still totally eludes me. Everything was feeling really good, until everything came apart. On a good fast reach back towards the marina I heard a loud crack and was instantly in the water. It was pretty clear what had happened. The rear rack arm had completely failed. Thankfully I was at the mouth of the marina and I was able to drift/swim back to the dock. Somehow in the process of the crash I broke the rudder off too. I'm not sure if it was breaking before the crash or if I landed on the rudder foil when the rack broke.

Sometimes I wonder why I don't get discouraged when Mothball One breaks, which it has many times. But at the end of the day I think its all part of the process. You can't push the limits without experiencing a few failures. But every time you take off and fly on a boat that you made, the fact of failures don't seem so bad, at least that's what I'm telling myself :)