Marine Forum

Repairing the transom on my Mirror dinghy

AquaBoy

23 September 2006 11:43:39

Joined: 17 November 2005 15:37:45 | Posts: 13

The transom on my Mirror has been leaking and suffering from rot down the outside edges. I have patched it a number of times, but I think it might now be time to do a proper repair.

Not having built a Mirror I don't know quite what to expect. However, it looks like there is a thin sheet of plywood that is attached to a more substantial piece of wood that makes up the interior of the transom. Can I just cut down the seams and remove this exterior sheet? Will this then expose the inside of the bouyancy tank allowing me to then make good any interior beading before replacing with a good sheet of ply?

Do I need to do anything to maintain the rigidity of the boat while I do this. Also while I have access to the inside of the tank what would be a good treatment to apply. I have noticed red paint flakes coming out of the bung hole after a session sailing. Would a wood preservative be better than paint.

Re: Repairing the transom on my Mirror dinghy

SeaDog

23 September 2006 11:45:31

Joined: 14 November 2005 14:23:57 | Posts: 11

I would strongly suggest placing a temporary brace across the gunwales to hold the boat shape before removing the transom. If taken out carefully you will have a ready template for a new one.

Re: Repairing the transom on my Mirror dinghy

Anonymous user

22 October 2006 05:31:56

Joined: Unknown | Posts: Unknown

>..it looks like there is a thin sheet of plywood that is attached to a more >substantial piece of wood that makes up the interior of the transom.
That is correct. The Mirror transom consists of a plywood sheet, together with an aft transom top that has most likely been attached with glue and copper nails.

>Can I just cut down the seams and remove this exterior sheet?
Yes. The transom is attached to the boat along the side and bottom seams and along the aft deck seam. When these are cut, it will come free. Be aware that the aft deck rests on a stringer attached to the transom, so you will probably need to cut through both decking and stringer.

>Will this then expose the inside of the bouyancy tank allowing me to
>then make good any interior beading before replacing with a good
>sheet of ply?
Removing the transom will expose the interior of the aft bouyancy tank. It will not expose the interiors of the side tanks.

>Do I need to do anything to maintain the rigidity of the boat while I do this.
Yes, you should support the gunwales so the sides do not bend outward. A good idea would be to nail or securely clamp a shaping strut across the boat near the stern.

>Also while I have access to the inside of the tank what would be a good >treatment to apply. I have noticed red paint flakes coming out of the bung >hole after a session sailing. Would a wood preservative be better than paint.
It depends on what the previous treatment has been. New Mirrrors built these days usually have their tanks sealed with two coats of clear epoxy as a "barrier coating". But epoxy barrier coating over old paint is iffy. Mirror Sailing Development (which markets wooden Mirror kits in N. America) also recommends sealing tank interiors with a good exterior grade urethane house paint (these are generally oil-based). It sounds like the original builder did this, in which case you should probably scrape the old paint as best you can and apply a fresh coat.

Some notes.

1) If you replace the entire transom, and do not retain the aft transom top, you might want to record the boat's hull number, which (by class rules) should be stamped on the transom top facing inward.

2) A class-legal Mirror requires two drainage holes like those in your original transom, just at the level of the aft deck.

3) Establishments that market wooden Mirror kits (e.g., Mirror Sailing Development) also distribute wooden replacement parts, like transoms. If you wish to purchase a premade transome with top, stringer, and inscribed hull number, you might want to contact them.

Good luck!

Re: Repairing the transom on my Mirror dinghy

AquaBoy

22 October 2006 08:43:36

Joined: 17 November 2005 15:37:45 | Posts: 13

That's great - many thanks for all your replies.

Re: Repairing the transom on my Mirror dinghy

Anonymous user

08 July 2007 15:23:29

Joined: Unknown | Posts: Unknown

Is it necessary to bolster the transom on a mirror to fit a small outboard motor?
How should it be done?

Re: Repairing the transom on my Mirror dinghy

Anonymous user

08 July 2007 15:54:47

Joined: Unknown | Posts: Unknown

It depends of course on what shape your boat is in, however the classic Mirror was/is sturdy enough to take a small outboat motor (2-3 HP), without further strengthening and without special steps in the building process. The aft transom top, where the motor bracket rests, is a thick, solid piece of hardwood, typically mahogany. The aft transom is braced by the aft deck, which is attached to the hull on three sides, and itself sits on an aft deck support internal to the tank. In short, the Mirror has a solid rear end,
You may wish to construct a motor mounting bracket that will allow the engine to be placed in the middle of the transom and clear the gungeon and pintel. There is an article from MIRROR MANIA, which shows one set-up. If you are interested I can post it on the Mirror Discussion Forum (http://groups.msn.com/MirrorDiscussionForum/), which BTW is a great on-line resource for this boat. If you are in the US, you might also want to visit US Mirror Sailing (http://usmirrorsailing.com/default.aspx).

Re: Repairing the transom on my Mirror dinghy

Anonymous user

08 July 2007 20:37:10

Joined: Unknown | Posts: Unknown

Thanks,
I believe my boat will be solid enough. Yes I would be interested in viewing the set up to mount the outbd centrally.
Thanks again for your reply.

Re: Repairing the transom on my Mirror dinghy

Anonymous user

10 July 2007 02:34:23

Joined: Unknown | Posts: Unknown

I have been unable to post the PDF on the Mirror Discussion Forum website. Use the Contact US facility of the UM Mirror Saling webpage (http://usmirrorsailing.com/default.aspx) and provide your email address, I can send you the document directly.