Proof of Concept

[daiquiri]

You have a nice boat there.
Do you intend to you close those openings in the bow and stern modules, to get a storage space and buoyancy in case of water flooding the cockpit?

[michael pierzga]

For rigging sails...perhaps a windsurfer rig would be worth exploring. They are very powerful and easy to store.

One detail of a small boat is the lack of space to store gear. Each piece of gear needs a double mission. I really like the idea of oars turning into masts. Perhaps a schooner rigged Optimist dingy type sailplan. Simple and when the wind dies unstep and row. Sails turn into cockpit cover when at anchor.

[daiquiri]

Did you think about the rudder? Where will you put it and how will you steer it?

[kvsgkvng]

Yes, indeed, the openings are going to be a covered watertight compartments. Two of each at the bow and stern. They will be separated by a vertical partition to provide extra redundancy in case of an accident.

I am thinking very hard how to use most of everyting making things work in two roles. It is not easy, because I would like make everything at least almost perfect.

I am still deciding about sail rigging. Not sure what to use but one thing is certain -- it must be simple.

I think ruder is pretty easy. At the worst I could use a conventional ruder. Esoterically, I could use two dagger keels, one in each detachable compartment. The aft keel would act as a ruder. How's that? I think it should work. But for now it is just a thought.

Thanks for cheering me, kind regards.

[ancient kayaker]

Good luck!

[kvsgkvng]

I did some research and here is the oar layout based on it. To me it looks a bit long, but it is my personal impression. I wonder, is it a good oar dimensions for the boat?
Thanks.

[ancient kayaker]

Some stuff about oars -

http://www.stivesrowingclub.com/Rigging.htm
http://www.bateau.com/free/simple_oars.html
http://www.shawandtenney.com/wooden-rowing-oars.htm

[michael pierzga]

Go flat bottom . Build in foam glass.

Fast, simple to build , superlight and stable when cut into sections.

[kvsgkvng]

Thanks for the oar sites. I found them to be very useful. Here I have the next step in designing my boat. I used suggestions and ended up with this scenario. I used one oar for the mast and the other for the ruder. I still have to decide about the keel. I guess it will be something like 12" x 30" daggerboard in the box.

I plan to slip the oar working as the mast in a box similar to one used for the dagger board. This slot will be placed in the detachable bow of maybe in the front of the mid-section. In this case the dagger board probably would be just behind the mast.

I am not sure where to place the dagger board. Pictorially, I could see it inbetween the mast and the mid-ship section. But someone with more boat design experience might suggest something better. Could someone at least hint where it should be, please?

Thank you very much!

[kvsgkvng]

Originally Posted by daiquiri

You have a nice boat there.
Do you intend to you close those openings in the bow and stern modules, to get a storage space and buoyancy in case of water flooding the cockpit?

Yes, I just did not show the covers

[ancient kayaker]

I have doubts about tying up both oars for sailing; sometimes you need an oar to help get through a change of tack or fend off a rock.

Also I question the need for a bowsprit; is it just for style? It moves the center of area of the sailing rig forward which allows you to move the daggerboard trunk forward as well; they must balance each other or the boat will only want to head downwind. It's always tricky with a new design to locate the daggerboard trunk correctly fore-and-aft. Te daggerboard's center of area is usually a little aft of the center of area of the sail. Once you are sailing you may find it necessary to make further adjustments in the sailing rig. One of the advantages of a leeboard is it can be moved, unlike a trunk.

There is a long distance between the steering oar blade and daggerboard. The boat rotates about the DB and with this separation it is going to turn slowly; being so light it is likely to stall during a change of tack and end up in irons.

You do not show a skeg and the bottom looks fairly rounded so when rowing there will be the opposite problem, the boat will tend to spin if the pull on the oars is slightly unbalanced.

I suggest you get rid of the bowsprit which is more appropriate on a larger boat, move the sailing rig and the daggerboard trunk aft, and have a regular rudder. That frees up an oar for emergencies, it will make the boat more maneuverable through turns, and the rudder can be left down to steady her for rowing, eliminating the need for a skeg. A simple device for locking the rudder can be added - this is what I do in my sail/rowboat.

One of the reasons small sailboats like dinghy's are so quick on turns is they have to be, as they stop in a few feet when headed directly into the wind. Older style heavier keelboats have the momentum to coast into the wind while they complete a leisurely turn.

[Petros]

oar for a mast is great idea, but as a rudder not so much (I tried this once), not very effective, plus what the Ancient one above said (you might need it).

Place the dagger board at about where the centroid of the combined sail area is relative to the hull. It should be about 5 percent of the sail area, in the example above about 3 sq ft. A rudder btw is about half that size, and is not so large that it would be a big deal to have one (that is not an oar). Make the rudder a lower aspect ratio than the dagger board so it is more stall resistant.

You are getting to have a nice looking boat. Looks like you are almost there, When you going to start building?

[kvsgkvng]

Originally Posted by Petros

oar for a mast is great idea, ... Looks like you are almost there, When you going to start building?

Hello friends,

First, I am not going to start building just yet. I am planning to build out of industrial insulation foam, glass and epoxy. So, the next task would be to build foam cutter (simple) and a rig to slice 4' x 8' foam sheets into ¼" thick strips. I also have problem with work space. Where I live to rent a place for building is kind of expensive. So, before start chopping wood, I need to think a bit more about where I am going to set up my shop.


In this post I am selecting the next stage for my boat – sail type and rigging. I have two types, which I am concentrating at: (a) standard gaff + jib and (b) cutter layout with two jibs + small main

The gaff (a) is very traditional and is understood well, the cutter (b) is somewhat unusual. I did an extensive research on the net before asking for second opinion here, because sometimes the replies are not neutral in its expression.

Internet search sources said, that cutter (b) has much better performance in pointing against wind while gaff (a) has very good downwind performance.

I noticed that the total area for (b) is 30% larger compared to (a). Combined longitudinal center of force is lower by 12% and transverse center of force is smaller as well for the cutter setup. I did not do any calculations because numbers would change a lot, but it was obvious.

In both cases (a) and (b) I placed the same vertical oar, acting as the mast, next to the bulkheads. In this case stress distribution would be more beneficial compared to placing the mast in the middle of a plate. I also placed the keel a little forward in cutter design (b) to make the sailboat point into the wind a bit better. I think that during very strong winds, in cutter setup, having small main is very beneficial in pointing the boat toward the wind.

If the middle jib is taken down, the total area of sail in both cases is approximately the same. I also read that a jib is working more efficiently compared to main (gaff) with less air turbulence around the sail.

Another good thing for cutter setup is that all sails could use furler rolling in pretty simple arrangement. Well, I am getting too much in details I guess.
Personally, I like cutter (b) better than gaff (a). I really would like to hear others opinions.

The stay setup is bettero for the cutter (b) because in the gaff setup I would not be able to bring back stays too far back, it would limit the gaff movement.

My question is “is (b) better that (a) in general; and if not, why?” Because everything to my mind says that (b) is better. But again I am not a pro.


Please, I am looking for any help.
All opinions are welcome.
Thank you very much!

[michael pierzga]

Windsurfer mast sail combos are cheap to buy, fast, and versatile. Two piece masts are easy to store.

Might be worth considering

[kvsgkvng]

Originally Posted by michael pierzga

Windsurfer mast sail combos are cheap to buy, fast, and versatile. Two piece masts are easy to store.

Might be worth considering

Thank you for the suggestion. I completely agree with you, but I have some restrictions. Sure they are good. No question about it. But I must fit the boat in 6.5'x5'x2' place and stuff oars somewhere along the bottom of a wall. I would not be able to do that with windsurfer masts.

One more requirement is to utilize all items as many times as possible. I could row with oars when there is no wind or the boat on extremely shallow water. Where I will store 15' mast on 12.5' boat?