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A QUESTION FROM FINLAND

A QUESTION FROM FINLAND

 

He ask if it is not better to have more dense material in rudder and centerboard as not to stability due to flotation.

 

Yrvind answer:

Heavier materials low down will give more stability. Added lead will give even more stability. In the case of the centerboard, when the board is raised, more weight will make the boat lose stability.

Almost every boat is designed as if it was to be a racing boat and the same with books about yacht design. Exlex is intended for cruising, when cruising I sail mostly down wind, even though I plan to round Cape Horn, 50° south to 50° south, east to west. Exlex is designed as a low energy boat and cruise at low Froude numbers around 0.3 this reduces the energy needed to about 1/6 of a conventional boat. See my Manifesto for a more detailed explanation.

More weight in the appendices will put more strain on them; they have to be designed more heavily. This added weight would make the boat slower down wind. It will also make the boat bigger and heavier and more expensive.

I think most boats are sub optimized for windward work. Neither do I think a cruising boat shall have weather helm.

Regards Yrvind

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WORK ON CB AND RUDDER

Here is a report on the progress on work on the rudder and centerboard.

Some photos below.

I used a NACA- profile with a cord of 400 and 40 beam. To simplify I used a piece of the rudder from my chinerunner I 2011 sailed to Martinique with. I had made the rudder rather long and this is a bit I had cut of. Even this rudder and CB is long, but it is very easy to cut of a bit and difficult to add so in my experiment I make the fins a bit long. I have glued a pice on the aft end and put 3 strips of masking tape at maximum beam to add 0.7 millimeter to make it lay flat on my table saw. Mowing the fence and raising the blade to touch the rudder piece I got a guide that helped me to copy and get a new NACA profile. With this help I cut the Divinycell after that I used a pen to mark the bottom of the cut then grinding away the rest.
Peter was kind enough to help me.
A side viuw.
From a different angle
Laminating, using NM-epoxy 3 layers 450 gram glas + one extra layer from the root halfway down. The Divinycell is H130 130 kilo a kubic meter. The work went fine.
Rudder and center board paiteintly waiting for more work to be done on them.

To be continued…

Regards Yrvind.

Please help to support my project. Kindly donate money on pay pal or Swish.

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DECK NOW DONE ON OUTSIDE

The deck is now laminated on the outside. Inside I have to do the fillets and taping so the boat is now uppside down once more.

I have also weighted the boat she came out at 426 kilos. That is to my liking becouse her waterline is 5.5 meters or 18 feet. There is not much more to add except the rudder and centerboard the hatches and a few odd and ends. Anchor and lead batterys will also add weight but a guess is that the painted boat will be about 600 kilos me and food and water for 60 days will add about 200 more kilos. To me it seams reasonable the she will weigh about 800 kilo at the start of a ocean passage. That gives a displacement ratio of 137.  Most cruisers land somewhere between 300 and 450 at the start of a passage, racers are lighter. The figure for to be able to plane given is belov 150. There are of course other criteria for to be able to plane as a suitable hull form. I think Exlex minor has such a hull. Where she does not shine is sail area to displacement, but wind pressure increases with the square of wind speed. Given enough wind and down wind she might be able to plane, but that is speculation. Hopefully I might find out coming summer.

Me in the fore hatch from where I can handle th fore sail. A tunnel through my bedroom and the saloon leads to the aft hatch from witch I can handle the aft sail. A safe lay out for a man born 1939.
Weighing the boat Aft measurment 285 kilos Fore measurment 141 kilos Distance between points 299 cm I use that number if I like to calculate longitudial center of gravity.  426 kilos total.

To be continued…

Regards Yrvind.

 

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PERCEIVABLE PROGRESS

I have been working on the ventilation systems for weeks adding piece to piece usually six a day to the ducts. The two ducts for incoming air and outgoing each cross the boat just below the deck two times, then incoming air is ducted down to the bilges outgoing air ducted from bilges up to the deck. There is also water seals to prevent air escaping but letting spray out. This work is not really visible , but it is done and I am finished with it and I am happy about that becouse it has been drawn out and made me work long houers. Also done is most of the work in my sleeping room and in the aft saloon.

The fore deck on the other hand have been done in a few days and have changed the look of the boat very much.

Below a few pictures.

One mold to help to give the shape of the fore deck.
Me mixing NM-epoxy. Magnus who took the picture helped me to lift on the fore deck.
The piece in position, wighted down. Next work is shaping the fore deck and then laminating it. The inside surface is already laminated. That was done on the table.

To be continued…

Please help my progres by donating.

Regards Yrvind

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NEW SEAL FOR TILLER

One reason I did a restart on Madeira was that the stering system jammed. Here is a better and lighter system. The rudder head has two pintles. The upper one is through the tiller and to the transom. That way the hole for the tiller to enter the cabin is minimal and easily sealed with a bellow. The picture show a model scale 1:2 of my transom. The two round rings indicate the windows.
This picture is more from the abowe. The torx screw on the transom indicates the pintle.

There will also be an outside tiller abouve for sheet to tiller and maneovring in tight places.

Four strong points have been added.
The hull is reinforced with several extra layers of glassfibre in NM-epoxy on inside and outside. There is large backing plates for the six M6 screws on the inside.
The strong points is made of 25 mm pipe. This helps to prevent chafe on ropes. I can lift the whole boat on any of the strong points. The two on the transom will be used in gales to tow chains. I have not used this technique before nor heard of anyone else using it but for a small boat I beliwe it is a good idea. Anywhay there is chain aboard for the anchor. The aft strong points is wery easily reaching standing in the aft hatch. No need to go on the deck. That would be cumbersome.
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AFT DECK

Most of the work on the aft deck abowe the saloon is now done. What is left is to fillet and tape the seams between the different panels to get strong connections.

Below two pictures.

Me laminating. Håkan who took the pictures helped me with the laminating. The job took rather longer than I had expected. Luckily Håkan had patience. Thanks Håkan.
This morning was spent running for conditioning, but in the afternoon I remowed the peel ply and cut a hole for the hatch. I also turned the boat upside down that I can work on her deck from the inside in comfort.

To be continued…

Regards Yrvind

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BYRÅLÅDSEFFEKTEN

Byrålådseffecten a english translation would be the drawer effect: This is what we engineers call the nuisance when a drawer gets stuck in a chest of drawers and it does not only happen to drawers; it happens to most sliding things that are wider than deep. It is a pain.
To avoid it I made an analyses and it turns out that the solution is surprisingly simple. Drawers that are wider than deep have little guidance and therefore not always move straight but turn. When they turn the short side of the drawer is not any longer parallel with the guiding sides. The drawer takes more space and gets stuck diagonally. The more you pull the worse the drawer gets stuck.
I said to myself: what geometrical figure does not get wider when it’s turned, obviously the circle, by definition. I use part of a circle segments have been cut away to make it almost like an rectangle. In this case when using it as a lid for the anchor locker I only lose 15 mm on the corners. Pictures will illuminate. A big lid would be to cumbersome so I devided into three peices.

Below some pictures.

Just for fun I did a simpel calculation using Pythogeras formula. I got 15 mm difference in the corners compared to a rectangle. That was fine. Of course it is more simpel to do it graphically.
Marking the corners to be cut with a compasses
The three pieces in place being now a strong easy handled lid for the anchor locker.
Finally holding down the lid with angle profiles of carbon fibers. The lid on the anchor locker is also my seat in the saloon. The two lunch boxes can be seen to left and right.

This idea of preventing narrow sliding broadside to jam can be used on many applications. Companionways are mostly shaped narrover at the bottom that the washboard will not get stuck by the byrålådseffekten. Its a bit magical how easy the boards now slide thanks to the rounding of the corners.

I have now started on the deck of the saloon.

To be continued…

Regards Yrvind

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ANCHOR STOWAGE

The anchor stowage is now mostly done.

Below two pictures.

This is howe I moulded the carbon to secure the sharp ends of the two biggest anchors.
Now the two anchors are lashed down and secured. There is also a winch and winch handels. Handy to get the boat afloat again after running aground or the opposite hauling her up on a shore out of reach of the waves. When needed the winch is bolted down on deck. After use it is returned to its locker. Keeping the center of gravity down.

Next step is to do the lid and I got a good solution for that.

To be continued…

Regards Yrvind

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STOWAGE

A place for everything and everything in its place. It is important to get thing secured and easily accesible. That requaries a lot of detail and that takes time.

The arrangement for my bedroom is now nearly done. Today I finished lockers for my note pads. They are in A4 format and square lined 5 mm. Kollegieblock we call them and I really love them. I have used them since the 50-ies. They are exellent for drawing boats on using scale 1:40. One square then has a side of 20 cm, half a square is 10 cm.

Ipad and small computers also fit there. Two of these lockers are on each side. I use sliding lids. They work well I have used them on a few boats before 1968 the first time and on Exlex now 2018. The present ones are made of Tufnol a nice material I find.

Below some pictures.

The two sides. Port side the forward locker open. Starboard side both lockers closed.
The closed one
The open one
On the starboard side is a place for a one liter water bottle, the daily ration. Later I will secure the lids and the bottle.
I have now started with the anchor locker. It is below my seat between the lunch boxes. The pieces of carbon fiber is to be used for laminating a down holder on the chisel points of the SPADE anchors. I will bring three, 5.5 kilo, 9.5 kilo and 16.5 kilo. I hope I have never to use more than the 5.5 kilo one. The 5.5 kilo anchor will live assembled ready to use in the forward part of the boat.

To be continued…

Regards Yrvind.