Eun Na Mara Footy

I’ve started work on my second footy. I sailed the first one at the WoodenBoat Show last summer. This summer at the WoodenBoat Show they are honoring boat designer Iain Oughtred at the tribute dinner. So I thought it would be fun to build and race a Footy based on one of Iain’s designs. Since I have a copy of the plans I decided to build an Eun Na Mara or Eun Mara as most builders call it. Just for reference, here is a full sized Eun Mara:

The plans I have are drawn to 1" = 1’. Since the boat is 19’8" I needed to shrink the plans I have to 60% to get the right length. This was too skinny for a Footy so I shrunk the body plan to only 75%. After shrinking the sections I cut them out and glued them to some 1/8" cedar molds and cut and sanded them. These were then mounted to a scrap of plywood and faired and lined out for planking.

Then I glued the keelson on, in two layers. The end molds and the stem molds will stay in the finished boat.

Then the garboards were glued on:

Steven

Hi Steven - good luck with the build. Looks very nice so far.

I noticed in photos you are using “G-Flex” and would like to ask your opinion and any observations you might have, of the stuff - if you wouldn’t mind sharing.

Thanks, Dick

I started out with the G-flex but then switched to some medium thickness cyanoacrylate (super) glue. It set so much faster, with the epoxy I felt things were going too slowly.

More progress.

Beveling the laps:

Gluing on the first plank:

Second plank:

The first one was epoxied and the second one super glued. I was worried about these planks splitting but a little soak in some boiling water and they bent right in.

Then more.

Steven

Still one plank to go but I had to pop the hull off the jig to cut back the ply of the jig:

I was amazed at how light the hull was at this point.

The sheer strake is mahogany:

I don’t usually use epoxy as a coating but thought this was a good exception:

Steven

After sanding down the epoxy the hull weighs 4.3 ounces. How does that compare with other building styles? My planking is 1/16" thick hundred year old poplar except for the mahogany sheerstrake and the cedar garboards.

Steven

Looks amazing Maine Footy! I am following this build. Can’t wait to see her progress. Thank you for sharing the build log.

Wilbur

Steven,

Not wishing to rain on your parade so to speak, but have you considered whether or not your hull will have sufficient buoyancy to carry the finished ready to sail weight of your Eun Na Mara Footy ? I ask because your bare hull canoe body weight is, you say, 4.3oz - which translates to about 122 grams. The only time I have completed a vaugely similar project to yours was when I scaled down the US1M Mistral to a Footy size. I used 1/16" thick Balsa strips to plank the hull and the finished canoe body was 21 grams. By the time I had finished the fitting out with a standard 2 ch AM radio and Alkaline batteries the ready to sail weight was 480 grams of which 200grams was in the ballast. Most people who build using dead trees will use 1/16" or even 1/32" balsa, or 1/32 ply. There are a lot of builders out there who can build down to 350 grams or maybe less but even for us mortals a 122 gram hull is still a distinct disadvantage.

In your first post here you mentioned scaling your drawings by 60% on length and 75% on beam and draft. With my Mistralette, where I was scaling from the full size US1M drawings, I used a factor of 3.3 on length - for obvious reasons - and then 1.6 on beam and draft to get the displacement I felt I was capable of building down to. When scaling an existing design, be it an existing model or the real McCoy, we are really stuck with a predefined waterline and hence have to rework the sections to get what we need in the small scale size. The problem I found was that this completely destroys the asthetics of the original with Mistralette being a bit like a bath tube compared to Mistral’s sleek slippery look. It did, however, sit correctly at its lines and performed reasonably well.

I think what I am trying to say is that on the basis of my experience I might have expected your beam and draft scale to be closer to 125% rather than your actual 75%. Mistralette ended up with a beam of 130 mm, But if I had really wanted a beam of 100 mm as you would with Eun Na Mara, then I would have increased the draft proportionally. I accept that you are probably not expecting to go racing with Eun Na Mara and may well be prepared to reduce my 200 grams of ballast weight, and if you stay with the scale sail plan then the heeling moment won’t be too great, but be prepared to add sufficient ballast to stop it falling over in a gust, and possibly more draft to carry it. A 3:1 length to beam ratio for a Footy is not at all outrageous although the draft to go with it is quite large - in your case about 120 mm.

I apologise if this smacks of me teaching grandma to suck eggs - but forewarned is forearmed.

Cheers,

firstfooty

Wow. There is lots to think on here. :slight_smile: I don’t know where to start so I’ll just jump in. I’m definitely not trying to build a high performance boat. I just want to make it around the course in style. I’m planning on using a standard footy keel. I’m thinking of the boat as a caricature of the original boat. The rig will be scaled to fit. The Razor I brought to Mystic last year was planked in 1/8" cedar. I didn’t weigh that hull but I have another bare hull that I built back then but never finished. I’ll weigh that one tomorrow.
The way I determined the scale was straightforward. I had to reduce the length to 1’. But if I reduced the width the same amount it seemed too skinny as compared to the Razor hull I had. So I made it just as wide as the Razor. I just took a couple of pictures:

I know it’s heavy but it doesn’t seem any heavier than the other one. It is extremely strong, though. :wink: You never know, I just might take the “Spirit Of Tradition” class. :cool:

I might make a display rig for on land and a separate rig for racing.

I’ve got to go look for a metric/inch ruler so I can visualize all your dimensions. :slight_smile: Scale, too.

The beam of the EM Footy is 5-3/8". It’ll be a little wider after the rub rail is on.

I’m trying to build light, really. It’s not easy for me.

Thanks for your thoughts, feel free to jump right in here all you other guys. All opinions are welcome.

Steven

Steven,

Keep in mind that any boat is a compromise, and there are successful Footys in every weight category, so while weight/displacement is certainly a factor, it is not the only determination of a successful design. The most critical factor in a boat’s performance is getting the delicate balance between the centers of gravity, sail area, and lateral resistance correct. This seldom happens right off the drawing board, but must be done by actual testing in various conditions and making adjustments accordingly. So far, your boat looks great, keep working at it and post the pictures as you go. Also keep in mind that a heavier boat can usually handle a bit more sail than a very light boat.

Regards,
Bill

Bill - I know you’re trying to be supportive here but you’re assertion, “that a heavier boat can usually handle a bit more sail than a light boat.” is misleading in this case. It is the displacement to ballast ratio that really determines how much righting moment a boat has and therefore how much canvas she can carry up to a certain wind strength. The original Razor that Steven used for volume comparison was designed to weight in at 450 grams +/-, with at least half the weight in the lead bulb. At 122 grams for the hull alone, sans internal structure, deck, keel, rudder, rig, batteries, and radio she is already at 1/3 of the Razor’s weight. Even if Eun Na Mara can handle floating at around 600 grams of displacement, which might allow about 200 grams in the bulb (if everything else is built light) and a chance of sailing upright much of the time, the displacement to ballast ratio will still not allow the boat to, “handle a bit more sail than a light boat.”, or for that matter the sail of another heavy boat. A low aspect rig without much area may be in the cards for Eun Na Mara, but skimping too far may make it hard to tack her. If anything I would go wider than scale not taller.

Steven - What I think you should do before you go on is to float your hull with weights and see how much weight she can handle before you feel she is too low in the water. Then weigh the hull along with those weights to give you an idea of the target weight you need to build up the rest of the boat to. If you can only measure in ounces then you should convert those numbers to grams, there are 28.35 grams in an ounce. Grams will help you to communicate in “Footy”, and the rest of us can help you more easily. While you’re at weighing it would be a good idea to weight the rest of the stuff (mentioned above) that will complete the boat. This info will allow you to determine the weight of the bulb, it is what ever is left over after you subtract the hull and all the other parts from the displacement weight.

I don’t mean to be discouraging here but you may find that you need to start anew. As Firstfooty pointed you may need more volume (breadth, hull draft, or both) to accommodate the lapstrake building method and arrive at a reasonable ballast ratio of 50/50. You might also consider using a lighter wood with this method. Poplar is very dense and therefore heavy. If you don’t like Balsa then Basswood might be an option. Its lighter in weight than Poplar and varnished it has a golden hue.

Sounds like it’s time to go out and get a scale. I got my earlier measurement from the local market. :slight_smile: Stay tuned.

Thanks,

Steven

I think being a builder of full sized people carrying boats is a handicap in this Footy business. I thought my EM hull was pretty lightly built. Wrong. I went out to ‘Bed, Bath and Beyond’ last night and picked up a $20 digital scale. I sure hope the logo on the scale isn’t indicative of my future racing performance. :wink:

(It’s a weight loss reality tv program if any of you guys didn’t know)

So my 1/8" cedar planked bare hull weighs 74 grams:

The Eun Mara Footy bare hull (with cabin bulkhead added) weighed 138! Ouch!

Next I weighed my Razor from last year, including batteries, radio and servos but no sail rig:

644 g.

Then I loaded up some c-clamps and a tape measure into the EM Footy until the weight was close to what I raced with last year:

648g

Then the float test in the kitchen sink:

Not so bad, eh? So if I really concentrate on keeping the rest of the build as light as possible and maybe use a lighter radio/servo combo I could keep going. Not trying to win regattas, just get around the course (and maybe not be dead last;))
So let’s have it, what do you think?

Steven

Hi Steven - A gram scale is a must for all model boat builders. That and a notebook. By weighing all the parts of a boat as you make them, and keeping weight records (and some sketches) you can track and improve your building skills. You’ll find that referring to your records will give you new ideas of how to build various parts to be structurally better and lighter at the same time or maybe leave them out altogether. For Footies, overbuilding is a scourge, “just enough” should be the guiding principle. A boat is the sum of its parts, and the lighter the parts above water then the heavier the parts below water can be as part of the overall weight.

I use an O-Haus Triple Beam Balance gram scale. Its actually one I liberated from High School science class thirty plus years ago. It still works like new although there is a lot of ware and tear on the finish. Mine has a tare bar which is an important feature. A tare is a counterweight that slides along a bar that is used to offset the weight of a vessel, like a cup or a pan, that would hold a powder or a liquid to be weighed. For weighing Footy hulls the tare is set to counterbalance the props I use to keep the hull from rolling off the scale. Essentially the idea behind the tare is to counterbalance a container, props, or whatever else that needs to be on the scale without being included in the measurement of the thing you want to weigh. The tare should be adjusted so that what is not to be part of the measurement balances to the level mark on the scale. Its also very helpful to have the weight set accessory that will allow you to weigh things heavier than the 610 gram maximum of the scale.

Triple Beam Balance Scales come in several flavors. Except for the tare bar mine is a very basic model. My school upgraded to the Dial-A-Gram type Triple Beam Balance which uses a dial to control fine one gram adjustments, so mine was probably not missed. I also have a newer one that I bought when I thought I had lost my original. It is from a later series, the 700/800, but is a manual scale just like my first one.

Triple Beam Balances are very accurate and I like them because you can see graphically what you are doing and have a range of adjustments that I can understand.

I think that you can probably find one of these scales for reasonable cost since a lot of schools are changing over to digital scales. Digital scales might also be an option for you but I think they are pricey in comparison to good old manual ones. Good luck with your scale search, a good quality gram scale will be a real help and is an essential tool in Footy building.

Steven - It seems like we posted at the same time. Actual weights are kind of an eye opener, aren’t they?

They sure are. I didn’t know that a AA battery weighs 24g. So the 4 batteries alone are almost a hundred grams!

Steven

Yup, and a 200Mah 1S Lipo weighs 5 grams and does the job for a few dollars!
Also 5gm FM receiver, 5 gm balanced rudder servo, 12-15 gm balanced sail servo with Power lever - less than 30gms!
McRig rig 20gms…
It’s all salvageable with technology, and at low cost

I took out the too heavy bulkhead and got out the plane and sandpaper. I’ve planed and sanded an extra 8g of wood off. Now down to 113g.

Steven

Maine Footy,

Given that your original stated purpose was to have a semi-scale boat (fashion over function, in a way), and that the many very expereince people here have properly identified that less is more when it comes to weight, perspective may be useful.

Absolutely being the newest of newbies to this wonderful thing called Footy’s, I have read just about every post online to learn all that I might to help me in the pursuit. From what I have read, I don’t think there is any question, from a scientific perspective, less weight is better. Many very educated folks here can point you directly to the scientific proof as it were. One thing that I find curious, however, is that I have not found any real world comparisons out there, this boat against that boat, that provides any input as to the actual difference. Not saying at all that it isn’t out there somewhere. Just that I have not yet seen it.

Is there a boat that has never been beaten that we can look to? Not that I know of. Is Angus Richardson’s Mooonshadow so dominate that we can say, with certainty, that the extremely light weight of the boat is the overriding factor in the speed or handling of the boat? If light boats are faster, in real world practice, it is a difference that can be measured? Or is it simply a theoretical perspecitive since the difference is so small that scientifically our laws, rules and formulae says it is to be faster, but we simply cannot measure it because it is so minute? The stock answer I generally receive is that there are too many variables involved to ever know for sure. But, we remain very committed to removing every last gram in our belief in the science.

My point is that you have a very nice start to what I am sure is going to be a very nice boat to own and sail. Doing what you can to make it lighter at this point is certainly worth a certain amount of effort. Will it improve the peformance. just don’t know. I love your boat and look forward to seeing it on the water in all of its glory, fast or slow.

Wilbur

Another trick you can use to get a scale sailplan that will sail was done by Comet Model Hobbycraft in the 1950s. They had a little boat (two, actually) called the “Gypsy Sloop” that had a scale-like sail plan, shallow draft, and just a small steel plate for ballast. Sailed great, looked great on the water. The secret: the sailcloth was porous, almost gauze.

Cheers,

Earl

Okay - Wibur and all, there seems to be some belief that the “educated folks” are in some mad dash to make the lightest boat ever. Light weight is better to a certain point (less immersed surface (read drag) = quicker acceleration, less wave making resistance, less mass to push downwind, etc.) but when you go too far then all the desirable aspects drop away. Too light and tacking becomes more difficult in any wind over ghosting, the boat won’t coast at all when the wind drops which leaves you in the same place with no wind, and a new breeze will likely blow the bow away from the wind before the boat begins to accelerate.

What the “experts” are really after is the best ballast-to-overall weight ratio that they can build. The object is to get the positive qualities and sail carrying (read tall, high lift rig here) that high performance classes like the M Class have, and to get there means striving for a similar ballast-to-weight ratio. Most new builders, and many experienced ones, overbuild their Footies. What Moonshadow illustrated is that those ballast ratios are achievable and that the forces acting on a Footy don’t require massive internal structure. Moonshadow is stripped down to the bare bones, everything that is not absolutely required is left out. I call it “just enough” building, and to build like that requires rebooting how one thinks about boat building.

All that said, I’m not sure that Moonshadow is the template for future Footies, just a weathervane. Yes, she won the EuroGP going away, but that happens sometimes and it sure helps to have a top flight skipper at the helm. Prior to that race though Moonshadow wasn’t doing all that well. Granted she was initially powered by several experimental rig configurations which is not the best idea when testing a new design (too many variables to tell what is helping and what is hurting), but in the GP she sported a correct looking, relatively high aspect ratio rig with a very nice sail.

Which brings me to my real point, the boat is not the major determinant of performance, the sail(s) are. Yes, a good ballast-to-weight ratio is important but if your sails are not up to par it won’t matter much. My friend, Scott Spacie, the current American Champion and the dominant Footy sailor in the NY/New England area, has worked out the magic behind McRig construction. He can plug any of his rigs into any one of his sizable fleet of Footies (some dating back 5 years or so) and all anyone sees of his boat is the stern. Now, rigs aren’t as sexy as hulls, but they are the engine that powers the craft and are as deserving of one’s attention, as much, and perhaps more so than the hull. A great rig on an average boat is preferable to a great boat with a crappy rig.

Which brings us back to Steven. I like Earl’s suggestion, its a bit of slight of hand but it seems workable provided you find a cloth that is non-absorbing. Something like cheese cloth (or other cotton fabric) would droop if it got wet and not fill well. As with all the other aspects of the Eun Na Mara project there will be a lot of wrinkles to work out before the boat sails around the course in style, but Steven, now that you’ve gotten us all involved we expect to see some shots of her on the water soon.