Repairing my Mirror Dinghy

[Ribbed]

Hi all

New to sailing (did a bit of windsurfing 30 years ago...). I have recently bought an old mirror to gain some experience.

I knew I needed to tidy her up a bit but I have since found rott in the transom that I need to address. The rott is around one of the upper drain (I assume!) holes including a section of the thin plywood part . Water has almost certainly accessed through the damaged drain hole. However, the stern buoyancy chamber prevents access from the inside. I also need to strengthen the transom I suspect, as I want to use my little outboard.

Can anybody tell me the best way to access the buoyancy chamber to reach the transom from the inside? The obvious answer is to add a plastic access hatch on the top but I'm wondering if there is a reason not to do that or a better way?

Many thanks for any advice.

 

[dunedin]

Putting one of the small round waterproof hatches on the vertical face of the tank is a common way of getting access fo repairs.

We put a small outboard (c.2hp) on the stern of a Mirror without any modification / strengthening so provided otherwise sound, should be fine.

 

[Ribbed]

Thank you dunedin.

Bit worried that the fibreglass seams may be close to end of life. Is there anything to stop me installing one or 2 larger hatches on the top to provide easy access?

My outboard is a 3.5 2 stroke (Yamaha Malta)

Many thanks

 

[VicS]

Thank you dunedin.

Bit worried that the fibreglass seams may be close to end of life. Is there anything to stop me installing one or 2 larger hatches on the top to provide easy access?

My outboard is a 3.5 2 stroke (Yamaha Malta)

Many thanks

There is a support beam running from side to side under the stern deck. This will limit, perhaps even rule out, fitting anything more than small hatches in the deck
There is also a small ply support in the centre if this beam.
I have fitted a hatch in aft bulkhead

I'll try to photograph the relevant bit in the building instructions . Will add it if successful

The boat was designed to take a small outboard ( I have a Seagull 40+ for mine) . No extra stiffening of the transom other that the hardwood top section is necessary.

I

 

[VicS]

Not very clear but hopefully shows what I mean

 

[Ribbed]

Vic S - perfect, thank you!

 

[Ribbed]

Take a look at this mess! The rotten section butts up to the starboard panels. Any suggestions how to fix it? Concerned about structural integrity. Excuse the fist coat of filer in the upper part of the transom

Rapidy concluding I should replace that whole corner top to bottom with 5mm ply and stick it using epoxy / battens. I probably should avoid cutting the bulkhead unless I can see that the fibreglass tape is giving up.. I guess a strip of fibre glass tape all the way round (sides and bottom) the outside wouldn't be a bad idea either (just a bit untidy). Where can I get marine ply?

All opinions welcome & much appreciated.

Many thanks

 

[Bajansailor]

Have you gone back to 'good' wood all around the area of rot?
I am thinking that you might have to take up a section of the top of the aft buoyancy tank on the starboard side to get access into the compartment from the inside. You will need this access to laminate the joint on the inside when you fit a new section of plywood.
If you mark out a neat rectangular area to take up, and then carefully cut it with a jig-saw, you could probably re-use the panel that you have cut out, if you glue in some support battens around the aperture on the inside of the tank - you could then bed down the panel with epoxy on to these battens.

Re fitting a new section of plywood in the transom - if you have access from inside the tank you could again cut out a neat rectangular area and then fit a new panel in this aperture with maybe a few mm clearance all around.
If you fit support battens on the inside of the buoyancy compartment first, then they could act as 'butt blocks' .
Do everything with epoxy and appropriate fillers. Add strips of glass tape with epoxy over the joints on the outside.
If you have a generous overlap on the butt blocks on the inside you shouldn't need to use glass tape on the inside as well.

Re getting marine plywood, I guess that everywhere is closed now with the lockdown? Do you still have to get epoxy etc as well?
If you have the epoxy, glass tape etc, and perhaps some bits of hardwood knocking around, you could perhaps make up your own plywood by laminating some bits of hardwood together to get the required thickness?
Not ideal, but 'when needs must'.......

Edit - I just saw the other thread on this forum about Mirrors -
Mirror dinghy.

In this thread is mentioned a thread about 'The Mighty Pippin' on the Wooden Boat Forum - there should be some good reference material in here for you hopefully.
An update on The Mighty Pippin

 

[ashtead]

I once had a dent in the bow section of our Mirror and as there was a somewhat smaller hole cut a ply square and place inside and then glassed inside before filling . If possible therefore maybe a ply insert in rear tank covering the stern quarter glassed in and then a ply patch on top of smaller size and fill edges . I don’t know if any mirror owners assoc still exists but if so might be source of articles on such items. Also do lookout a copy of Mirror mania for other ideas to primp your mirror into an overnight cruiser etc.

 

[AntarcticPilot]

Where can I get marine ply?

All opinions welcome & much appreciated.

Many thanks

It's worth checking with your local BIG Builders merchant. In East Anglia, I've bought good quality marine ply from Ridgeons. Not decorative, but appears to be what it should be. But go for a place with a good local reputation, and ensure the ply is stamped BS1088 and has the kite-mark; that way if it isn't to BS1088, you can complain to Trading standards!

You'll probably have to buy an 8'x4' panel.

 

[James_Calvert]

Google Trident marine, they do kits and bits for Mirror dinghies. The marine ply transom panel on its own would cost £31.

Lots of other Mirror specific advice available on the internet, I came across one very detailed description of a transom replacement.

 

[oldbloke]

The easiest solution by far would be to screw and epoxy a new transom over the outside of the old one.
As Antarctic Pilot says B+Q style marine ply will do the job if well sealed with epoxy fillets round the edges. Not a purist approach but will last as long as the rest of the boat and will beef the transom fot the outboard

 

[AntarcticPilot]

The easiest solution by far would be to screw and epoxy a new transom over the outside of the old one.
As Antarctic Pilot says B+Q style marine ply will do the job if well sealed with epoxy fillets round the edges. Not a purist approach but will last as long as the rest of the boat and will beef the transom fot the outboard

Just to clarify things, while B&Q ply may be ok, I recommended going to the local good quality builder's merchant, such as Ridgeons in East Anglia. It's worth going somewhere with a reputation to uphold.