Broken Mast Step

[james gilchrist]

Hi All,

Could I beg some advice.  As most of you know I am building a coot.  However, at the start of the build I traded my Enterprise for an Oughtred Shearwater.  It has the balanced lug rather than the gunter sloop so has an unstayed mast.

The mast step has caused me some problems.  The mast step is a block 3 inches wide by 5 .5 inches long.

It is not glued in position but is screwed into the hog.  It is fixed by two bronze screws.  They are 2.5 inches long and I would guess gauge 10 screws i.e. just under 5mm diameter.

Under very moderate winds I have managed to bend the screws and rip them out of the hog.  I swore gently and very grateful I had just fitted oarlocks and oars.  I can't imagine how long it would of taken to get home the 8 miles up Coniston in the dark with a single paddle.

Looking at the hog and keel I can establish they have a combined depth of 1" 5/8ths.  The current screws enter to a depth of 1 inch.

So how to fix the mast step in a stronger way.  My thoughts thus far are as follows.

If I go to three inch long screws that leaves only an 8th of an inch of wood under the screw which worries me a bit, I suppose I could also countersing further into the mast step to enter the hog and keel a bit further but how much further?.  I could definately go up in terms of gauge of screw to say a gauge 16 which is 7mm diameter.  

Any advice greatefully recieved.

Yours

James

[Paul H (admin)]

I suggest you glue and screw some hard wood to the hog, then you can use deeper screws. I prefer modern twin thread screws because they grip well.

Paul

Sent from my HTC

[Timmo]

Bronze is certainly a fairly soft metal to take the strains imposed and only two screws with no glue does seem too little fixing. Stainless steel screws are harder (though more brittle) so may hold better. Others may have better advice based on a greater understanding of metallurgy.

I'd include some epoxy in the fixing. The mast step in my Acorn skiff is simply epoxied in place and hasn't shifted yet, though it may not be placed under the same strain as yours.

I'm also a fan of hardwood dowels. Glue the step in place, drill straight through for a couple (or more) dowels and glue them in. It would be a good way of reusing and sealing the existing screw holes. The dowelling will help stop lateral movement and reinforce the epoxy fixing. Wood in wood is generally less likely to cause long term issues with water penetration, rot etc. than metalwork. Hard to undo though!

Paul's suggestion of adding a hardwood cap to the hog and attaching the mast step to that (glueing and dowelling) sounds good. Should there be future problems you wouldn't be taking more chunks out of the hog itself.

Tim.

On 6 Nov 2011, at 13:30, adminHBBR [via UK HBBR Forum] wrote:

> I suggest you glue and screw some hard wood to the hog, then you can use deeper screws. I prefer modern twin thread screws because they grip well.
>
> Paul

[james gilchrist]

Thanks Tim, I did wonder about setting some big fat stainless steel bolts into the hog bedded into epoxy and then some nuts on top.


I will keep pondering and more importantly let you know if any of them work.  I think I will strip back the hog and epoxy the mast step in place as well as any fixings.


Cheers


James

[Timmo]

Hadn't thought of bolts. Certainly unlikely to sheer them. Wouldn't want to dig too many big holes in the hog though. Perhaps worth mixing that idea with Paul's extra hardwood pad. That pad could be made longer than the mast step to create a bigger glue surface for the connection to the hog. The bolts can then be through that pad.

let me know what you do and how well it works.

Tim.

On 6 Nov 2011, at 15:17, james gilchrist [via UK HBBR Forum] wrote:

Thanks Tim, I did wonder about setting some big fat stainless steel bolts into the hog bedded into epoxy and then some nuts on top.

I will keep pondering and more importantly let you know if any of them work.  I think I will strip back the hog and epoxy the mast step in place as well as any fixings.

[Paul H (admin)]

There is a sheer force on the mast foot which causes it to twist and lift on one side - so its support needs to be as wide as possible to improve leverage e.g. epoxy it in place and use bigger screws as suggested.

Additional screws will take some load off the current screws, so drill and screw extra holes if possible.

-Paul