BR20 mizzen mast rake

[Andy Stobbart]

Can anybody please tell me what rake is given to the standard BR20 mizzen mast? The measurement I am hoping for is the angle between the deck behind the mizzen and the mast as this is the easiest measurement for me to check on my boat.

[Graham W]

Andy,

Congratulations on your NZ purchase!

This may (or may not) help https://www.swallowyachtsassociation.org/smf/index.php/topic,1930.0.html.  With the main mast it’s possible to get the rake wrong.  However, the standard fixtures on my GRP BR20 are such that there’s no choice on mizzen mast rake - if it’s properly slotted into place, the mizzen should lean slightly aft. 

I don’t know if this also applies to a Denman wooden version.  If you don’t get a reply here from one of the several Denman BR owners, you could try asking Andrew Denman directly.

[Andy Stobbart]

Thanks for the quick reply!

Here’s a long explanation of the background to my question!

I am not trying to tweak the rake: I have damage to the bottom of the box that the mast drops into - the mast has bashed the bottom of the box through, splitting the plywood open just above the rudder assembly.
I think this is a weak spot in the design or construction. It seems to be caused, in part by the thin plywood of the bottom of the box and in part by the bottom of the box not being square but angled up towards the bow of the boat. When the mast is dropped into the box the front of the mast foot makes contact with the bottom of the box rather than the full width of the mast foot spreading the contact load.
What I need to do is repair and reinforce  the split epoxy ply at the bottom of the box but it is not an easy place to get to from above or from either side. From below with the rudder removed there is access but not much space to work!
My plan is to pour some liquid epoxy resin into the box from above (taking care to maintain the drain hole). This will drip out through the cracks and I will then apply firm upward pressure from the outboard well (using a jack!) to set the cracked piece of ply back in place while the epoxy sets.
I am hoping (expecting!) that another inch or so of fibre reinforced epoxy into the bottom of the box will adhere to the sides of the box sufficiently well to prevent the mast crashing through the repair in the future (anyone’s thoughts on whether my assumption is correct would be welcomed). Also I do not expect that an inch, or even two, less depth in the box will put the mizzen mast at undue risk due to the extra leverage on a shorter area of support at the base when sailing.

HOWEVER…    …what I would like to do is try to get the surface of the set epoxy in the bottom of the box to be as square as possible to the rake of the mast so that I can reduce the risk of repeating the same point of contact loading that has possibly contributed to the cracking in the first place.

Hence my desire to know what the mizzen mast rake calculation should be if anyone knows it.

I can, of course, estimate it visually by putting the mizzen into the hole and then tilting the trailer to get it more or less vertical before pouring the epoxy.

BTW if anyone knows how to contact Denman Marine other than via the phone numbers/contact form on their website I would be very pleased - I have been trying to make contact about the boat in general but have drawn a complete blank using these methods!

[Kit]

Hi Andy,
I own the second Bayraider 20 built by Andrew Denman - 'Little White Lie'. Wonderful build quality in common with all his boats. It is still in great nick. I am across the ditch from you in the Blue Mountains, west of Sydney.
The rake angle you are requesting is 86 degrees on my boat. It is determined by the angle of the aft wall of the mizzen mast step assembly.

I have purchased marine ply from Denman Marine on a couple of occasions. The contact details that I have used are:
Andrew Denman - andrew@denmanmarine.com.au
                           +61(0)413765985 or +61(0)413765984. This second number is the one posted on the Denman Marine entry in the Worldwide Classic Boat Show currently in progress.

John Britten        - clc@denmanmarine.com.au
                           +61(0)407245125
 Hope this is helpful.
                     

[thewatts@iinet.net.au]

Hi Andy,
I have a BRe, Denman built, which on arrival new in Perth Western Australia had suffered the same damage during road truck transport from Hobart. We discovered the problem as we were rigging for our maiden sail.l managed to get it repaired by a local wooden boat builder Tony O’Connor of O’Connor Wooden Boats.l have spoken about this with Tony and he would be happy to discuss what he did for “Cool Change”.
Kind regards, Ken Watts

[Matthew P]

Hi Andy and Ken

Ouch! 

Is it possible to support the mizzen mast with a collar secured around the mast, bearing onto where it emerges on to the deck?  Would this enable clear space to be under the mast foot to allow drainage? 

I appreciate it would be necessary to have, or create, a flat and possibly reinforced area on the top of the deck to spread the load of the mast.

Matthew
Tarika BR17

 

[Andy Stobbart]

Hey thanks for all the responses to my post!

I have done a botch fix as I described by pouring epoxy into the mast base hole with a plastic tube stuck down the drain hole which I then removed when the epoxy reached a toffee-like consistency.

I first let some of the epoxy drain through the split timbers into the outboard well (drips caught on a plastic sheet that I spread there for the purpose), then I pushed the cracked and now glue-infused ply back into place which was very easy and held it there with firm ish pressure from a car jack while the epoxy went off. The next day I put the plastic tube back in and added a bit more epoxy into the bottom of the hole for good measure.

Then on Friday I rigged up and went sailing so for now as least the fix seems to have worked well enough and it is invisible unless you look upwards through the tiller hole in the transom or peer into the mizzen mast base hole with a torch.

Fingers crossed ? and thanks again for the help and advice.

Final thought: I will try to get hold of Andrew Denman and mention the issue to him because it seems to me that this is a bit of a weak point in the design/construction that he may want to address before making any more boats…. but if anyone else has his or swallow yachts’ ear perhaps they could draw attention to the issue in case I don’t get through.