Mirror 16 Build

Hi Sam , I am Peter from Brisbane Australia. My dad built a Mirror 16 and we launched it in 1967. It was built using the stich and glue method with 2 inch fibre glass tape seams inside and out, with 3/16ths marine plywood hull. painted with PolyUrethane paint. Some builders coated the hull with Dacron and epoxt resin. The swinging centerboard was a great design as it operated like the swing wing on the Macdonnel Douglas F111. When planning downwind the board was retracted to cut down drag. We still had the boat up into the nineties but it expired from dry rot as water got into the boyancy tanks below the self draining cockpit.
It was afast, fun , seaworthy machine and I loved every minute of sailing that boat, and we had some very exciting times surfing big ocean waves, and indeed sailing in strong winds across our local Moreton Bay. Very seaworthy , very safe and we had a boom tent that made camping on board comfortable.

 

That would seem to be exactly what the Mirror 16 was designed for and sadly,the typical demise, because the quality of the ply with the kits wasn't great.

 

Hi Peter. That sounds like a blast.

I was hoping to start building it this month but it got too cold in the garage to refinish my other boat. So I'm waiting for the garage to warm up enough that paint will dry (probably another couple months). In the meantime, I've been working on a set of plans that should more closely match the original boat (centerboard and case, adjusting the geometry to satisfy the class rules and part sizes listed in the packing list better, etc.) Hopefully, I can have that ready to post in a week or so.

 

Attached is the first draft of the original plans. I still have around 5hrs of stuff to finish drawing and adjusting. (Things like boat cross-sections, spreader geometry, adjusted deck beam geometry, dimensioning, etc.) The shape of the centerboard is almost a complete shot in the dark. From the instructions, I've come up with a very rough shape, but actual measurements of one would be much more helpful.

Edit: stl files of some of the assemblies added for 3D clarification.

 

Hi Sam,

Congrats on all the hard work you have put into developing the plans, you are clearly a man on a mission.
We have M16 #261 and have cruised the coast of BC over the last few years in it (just got back from a 3 week cruise last week). From that I have some comments, suggestions on your "revisions" to the original design.

1. First and foremost i would keep the swing centreboard, I don't know how many times we have been really glad we could swing it up quickly and easily and in particular partially up. On our small mirrors with the daggerboard we have on occasion cursed the board when we had them partially up and had to tack.
2. The two boards on the floor that separate the forward and aft sections of the floor are a pain in knees when you are tacking, they would be much better located back a bit to be in line with the thwart. Yes that does mean you need to modify the limber holes in the top of the centreboard trunk.
3. You seem to have moved the thwart back, wont that push the helmperson back further? We have found that keeping the transom from dragging is critical to good performance. I would suggest you keep it as originally designed.
4. we have not done it, but adding a storage box spanning between the seats at the transom like the wayfarers have would be a good improvement for storage of fenders, anchor etc. I am planning t make one that fits into our boat sliding on wood rails like a drawer till it hits the transom and then locked in place with some wood fiddles. I will have feet on it so the water can drain to the transom under the box.
5. We added two rowing stations when we entered the Race to Alaska a few years ago, one used the normal thwart and the forward one uses a removable seat centred on the stay reinforcement block. Neither are sliding seat systems. I must mention that a M16 is a horrible rowboat. It rows at about 2.2knots and seems to need a bit of centreboard to track at all straight.
6. Suggest adding two inspection ports in the floor right close to the transom to increase ventilation under the floor. You are never able to drain all the water out of the tank (if any gets in) and the additional air circulation just helps to reduce rot.
7. On ours we added thin plexiglas sliders over the storage cubbies in the sides of the seat. They are not totally waterproof if you flip the boat but they do keep the rain out as well as the stuff in, and you can see what is in there. Plus the seat stays smooth for easy sliding for and aft. Having multiple cubbies seems to work for us, rather than the big ones you are considering.
8. We also added two reef pints to the main, and have used them both at various times along with the jib roller furling.
9. The battens on the floor are a pain literally on your knees while tacking and when sleeping in the boat. We cut some of those interlocking foam floor tiles to suit the floor and they soften everything enough to make life OK. I might well put the battens under the floor if i were building a new boat.
10. The big cleat on the foredeck snags jib lines with regularity, we replaced it with a custom bit of wood that we tie the mooring line onto but is smooth and non snagging.
11. We also added limber holes to the transom on top of the seats to encourage water to drain out not into the boat.
12. I would also suggest you spend some effort eliminating sharp corners that accumulate dirt through use of epoxy fillets and rounding of parts. Makes the cleaning so much easier. To that end i would suggest adding a nice big radius to the edge of the seats so if you are sitting on the floor the seat does not dig into your back.

I do have the original building instructions if you are interested (no we didnt build it).

I suspect that is enough for now,

cheers

 

Hi Dan, That's an excellent list of suggestions and information. I have been working on a set of plans that stays as close to the original as possible with the idea that it would give me a good starting point for making changes.
- I'm coming back around to the centerboard idea (I still don't really like how big the slot is but I think I could reinforce the corners around it enough to make it a non-issue).
- Do the baffles need to be as tall as they are? With the centerboard slot extending most of the way under the thwart it should be possible to slide them back a bit.
- The instructions I have say the thwart needs to be installed with the aft edge 5'-8" from the outside face of the transom. The thwart location isn't specified in the class rules, though. If yours is different, let me know.
- I like this idea.
- My only reason for having oars and oarlocks is because I prefer rowing to paddling.
- I agree. I've been debating about whether to put the inspection ports by the transom or up near the other floor ports (on the other side of the solid floor rib) where it might be easier to get in with a sponge and mop up the last of the water. I've also been wondering about having two openings (two ports or a plug and a port) per air tank so it is possible to force air circulation through the tank when trying to dry it out.
- The plexiglass covers sound like a great idea.
- I'm planning on reef points for the sail.
- I think it would be possible to put the battens under the floor. It would just take more work to get everything to fit and be waterproofed in the tank.
- I'll keep this in mind. (and may add a note in the plans)
- I think this sounds like a great idea. I may add this to the plans.
- I was planning on doing this everywhere the seams are glassed just because it results in a better joint. I'm a little worried that adding an epoxy fillet where there won't be fiberglass might make the joint susceptible to cracking around the fillet. Do you think caulk would work (or be too soft)? Maybe it might be worth it to use 2oz or 4oz fiberglass tape at non-structural joints to smooth the fillet and prevent cracking. I'm definitely planning on rounding the seat corners (do you think 1/2" radius would be enough?)

If your build instructions look like what is at the link below, then I have a copy. If yours are different, I would appreciate a scan.
http://www.ancestrypaths.com/wp-con...16-building-instructions-scanned-May-2016.pdf

 

Hi Sam,

Glad you like some of my suggestions......

• stiffening the ends of the centreboard trunk with wood block, and epoxy coated cloth should not be a big deal. I do recommend making the clearance to the centreboard corner and the trunk as the board is lifted bigger than 1/4" to allow for any rearward shift in the board rotation point after you hit bottom hard and want to lift the board. Ours is very close and i have gotten really good at repositioning the board slightly while drifting aimlessly in a harbour. The grooves the ss pin assembly slide down into have become worn in ours and thus the rotation point is easy to move back on impact.
• re the baffles, yes just move them back so they are under the thwart. That changes the locations for the limber holes into the centerboard trunk and does not cover the splice in the floor plywood, but no big deal.
• putting the battens under the floor would not be a big deal when building the boat as long as all the parts are epoxy sealed before they are assembled.
• re vent holes in the floor, i would suggest holes as follows: 1 in the forward bulkhead, a bit larger would be better to enable easier access to the plugs in the bottom, 2 on the middle compartment forward of the mast kingpost (one on each side), 2 as shown on the plans just aft of the kingpost (one on each side) (note these ones are excellent for keeping stuff cool, we call them the fridges) and 2 just in front of the transom to enable good air circulation through those two long compartments.
• we added reinforcing blocks under the gunnel which are glued to the gunnel and ply to support the oar locks. The glue seems to have been good enough to prevent cracking, but i agree that taping the fillets would make them stronger. And yes the boat rows better than it paddles, but that is not saying too much......
• Unless you have the original custom trailer/dolly i would also move the eye at the bow further up the bow stem. With it as originally shown the winch on most boat trailers will lift the bow rather than just pulling it.

I found your "original" plans and have had a bit of a look at them. I do have one comment on the lines. Just looking at the bottom from 1-5 ft back of the transom i question if the bottom is slightly concave bow to stern rather than a very shallow convex curve. I have not opened the cad files and done some detailed examination so it may be an optical illusion, but concave would make the boat slower.
I also note you dont show the dodger or the tent details, but hey maybe that is coming after the boat is built.

let me know if you want pix of anything except the centreboard (unless the board is down I can not lift it out of the trunk, so doing it on land means i need to turn the boat on its side.)

cheers
dan

 

I was planning on glassing the inside of the centerboard trunk. I wonder if making the centerboard grooves out of thickened epoxy would make them more damage tolerant.
I've been debating about separating the mid and aft air tanks at a different rib (rib 36 maybe). In the original design the solid rib that separated them was located near the fore end of the centerboard slot. I've considered making the rib closer the the center of the centerboard slot solid then placing four hatches (one each side of the centerboard and each side of the solid rib) in the middle of the boat. In my mind it would serve a dual purpose of having access to the deepest parts of the four floor air tanks and having the holes in the floor occur in a location where the floor panel isn't as stressed. The would end up being in a more high-traffic area, though.
The keel and chine lines look pretty straight for the aft end of the boat in the plans. There is a very slight convex curve, though. (The curve is a bit over 3/8" on the convex side of straight in the aft 4ft of the keel and chine).

I have made some headway on the centerboard shape. It's still a guess but at least it's a more accurate guess. Measurements of your centerboard would be very helpful, though. I'll attach my updated plans. The overall centerboard shape is dimensioned on sheet O-13. I would like to know if any of my dimensions match your centerboard.

I don't have any information about the dodger or tent at all. I'd need measurements of the component parts, what they are made of, how they attach to each other and the boat, etc. That or a bunch of pictures of the parts with a tape measure in frame for scale.

 

Wow! What a thorough job.It wouldn't be that much more work to extract the panel shapes for export to a CAM program.I doubt it would take two hours to cut the parts once that information becomes available.

 

Hello Sam, my name is Bert Oosthuizen, I am from South Africa. Have you started building the Mirror 16? I am considering the same, I am curious. Bert

 

Hi Bert, I haven't started building the Mirror 16. I would like to but at this point it is unlikely that I will get around to it. I have two other boats (one fits the family very comfortably) that are fast and fun.

 

If one build a boat from the drawings that is available on this forum, will you be able to register the boat somewhere, and obtain a hull number?

 

The most recent plans should meet the class rules. The Mirror 16 class isn't active. You could check with the Mirror Association and see what they are willing to do about a new Mirror 16. My guess is not much. Most of the rules require getting a kit from a certified supplier or buying a completed new boat from a certified builder. Scratch building wasn't allowed. I'm not sure if Barrie left anyone in charge of his database of M16s, who could assign unofficial hull numbers for plan built boats. My guess is that unless enough interest is shown for the M16 that the association starts providing kits again, any boats built from these plans would be registered locally and only raced as part of an open dinghy class.