Still talking about oars!

Above is an image of the recommended hardwood/softwood oar, courtesy of Topher Dawson, complete with the photographer’s shadowy signature.

The oars that we will build are very similar, except that we won’t be having the ball and slot oarlock system devised by Topher, nor his spoon blades.

For that system to work perfectly it’s essential for the pins to be absolutely vertical, something difficult to achieve, given differing crew weights, for example an exceptionally heavy cox brings the skiff down at the stern. Also it’s more difficult to make accurately. Correctly set up, the system works perfectly and smoothly, but we have decided to stick with simplicity.

For those who are interested, here are details of the ball and slot system:

We intend to adopt the pin and gate oarlock system devised by Don Currie, shown here:

Here is Don’s drawing, showing construction details:

You will see from the photograph that Don has made wearing strips from some hardwood. We could use oak, or perhaps source thin strips of polypropylene, which the rules allow. He has provided dowel spacers held by strong woodscrews and the photograph shows plastic bushes round these.

These details are not today’s problem, but will give us something to talk about while getting on with the main work. In the meantime please be thinking about sourcing suitable  polyprop, plastic strips etc that can be recycled for a seagoing future.

We have now sourced sufficient Douglas Fir and Western Red Cedar to make our set of oars.  The first task is to make a cutting schedule, so that the wonderful Mr H in his mountain workshop won’t get annoyed at having his time wasted.

Marking out precisely and very carefully where you are going to cut is far more important that just charging ahead and possibly wasting expensive material. The old adage “measure twice, cut once” applies.

We have more than enough WRC, as I had to buy two pieces – timber yards won’t just cut off the length that you need. We’ve got just enough DF to produce four handles plus strips to go on the front and rear faces of the WRC, to protect the latter from dents and bashes. The strips should be 5mm or probably 6mm thick if we can manage to get that width out of what we have. Each saw cut costs you the width of the blade, about 3mm or 4mm usually, rapidly using up stock.

We will soon run oar building workshops, but for these to be of any benefit it’s important that people understand the problems and help with solutions. As  start please read Topher’s detailed instructions, copied below. We need to modify these somewhat, to take account of the flat blades, and adjust the dimensions to allow for the DF faces on the WRC.  For example I’m inclined to make these faces full length, for strength and ease of building, rather than just the length of the outboard, WRC sections. This means that the handle stock would be machined 78mm x 45mm rather than 90mm x 45mm, allowing for the two 6mm strips.

Here is an image of the handles, per Topher:

 He is suggesting ovoid, 40mm for and aft by 35 deep. I think we should go slightly less depth and also produce a pear-shaped end.

There follow Topher’s Instructions. Please note carefully the suggested dimensions, especially at the outboard end. It makes me think that our current oars are massively over-strength!

Making the Beta test hardwood/softwood oar shaft for the St Ayles oar

The hardwood/softwood shaft has a rectangular cross section with slightly rounded corners for its whole length, tapering down in depth and width towards the tip.

  • The inboard section inside the boat is made of a dense hardwood like oak or ash and the outboard section is made of a light softwood like Western Red Cedar (WRC), spruce or Douglas Fir (Oregon pine). This improves the balance.
  • The number 2 and 3 oars have the thole pin mounted not in the gunwale but in a block screwed and glued to the inside of the gunwale. This moves the pin inboard by about 70mm which allows the oar to be shorter and therefore lighter than current oars. It also allows the bow, 2 and 3 oars to be the same length, 4.3m. The stroke oar is 4.0m. “Short oars” are all 3.5m.
  • The depth and width at each station along the shaft are the same for all lengths of shaft, but the distance between each station varies with the length of the shaft.
  • The spoon blade is a spooned narrow Macon shape made from two blade halves of 4mm plywood. The blade halves are stitched together with cable ties to form a shape which is curved longitudinally and slightly vee shaped in cross section. This is then epoxied and the cable ties removed. The curve allows the light plywood to be stiffer and stronger than a flat blade and more efficient in the water. This light blade contributes to the light balance of the oar.
  • A flat 4mm ply blade can also be made.

Making the hardwood/softwood shaft:

Whatever species of timber is used, it has to be clear of knots and straight grained. In the UK the most likely timbers for the inboard are ash or oak, but elm or beech could also be used. Outside the UK there will be favoured local woods of at least 700kg/m^3 density.

The outboard timber needs to be light, straight grained, clear and available in lengths of 3.5m, although they can be scarphed. Western Red Cedar, spruce, and Douglas Fir all fit this bill. WRC is the lightest, spruce is the most expensive, and Douglas is the heaviest. Slight variations of the width and depth of the tapered outboard are in the design to take account of the different density, strength and stiffness of the three timbers. If you are using other timbers, measure the density and stiffness of a sample of your timber and pick the design for the timber which most resembles yours.

The procedure depends on what dimension of timber you start with. If you use 100×50 thicknessed down to 90×45 then make one 45mm face straight, flat and at right angles to the 90mm face. Use this face for the aft face (nearest to the cox). Mark the stations on it and draw the widths at each station. Cut this taper leaving enough timber to plane to a smooth curve. You may want to use this blank to draw around on the other shafts.

If you are using Western Red Cedar in the commonly available 150×25 sawn finish house cladding plank size, you will need to thickness it to clean up the sawn surfaces and then glue two layers together to make a blank. Your blank will likely be a bit under the 45mm thickness needed near the gunwale, but only short padding pieces 150mm long are needed because it thins rapidly.

Then on the fore and aft faces, mark a centre line and set off the depth equally on both sides of the centreline. You want to take wood off both sides, perhaps with a hand held power planer to begin with, and then a hand plane as you get near the line. Finally you knock off the sharp edges with a hand plane and some sandpaper, aiming for a 5mm radius or whatever seems right. This is to make the oar shaft more robust against knocks, and kinder to rowers.

The oar needs a big scarph joint just outside the gunwale where the hardwood meets the softwood. This is just like the scarphs in the skiff planking but bigger. Make sure the final oar is straight!

It is easiest to make a hardwood blank 90x45x1500 and work the end down to the handle size, make the slot and line it with 3mm plastic, and make the scarph, before gluing it to the outboard.

Dimensions:

This table shows the width (fore and aft) of the shaft at each station, in mm. Station 0 is at the gunwale, and the ten stations are equally spaced going out from the gunwale to the tip of the oar. The cross section of the oar is everywhere rectangular, with  slightly rounded corners, about 5mm radius.

The depth of the shaft (top to bottom) is exactly half of the width at every station.

The inboard part of the oar, from the handle end to the gunwale, is hardwood of a constant 90×45 rectangular section.

 

The dimensions vary a little for different timbers, to take account of the different density, stiffness and strength of each timber. It is important to avoid knots, especially near the forward and aft faces of the shaft.

pastedGraphic.png

 

If making this oar out of Western Red Cedar, the lightest of all three timbers, the shaft can be made of two layers of 150×25 plank which is the most commonly available size, used for house cladding. It needs to be thicknessed down to clean up the surface, but taking off as little wood as possible. Depending on the plank, you may end up with 19-22mm thickness. A small section on each side may be needed to thicken up the 150mm nearest to the gunwale to make 45mm.

The oars come in three lengths. The shortest, 3.5m, is for short oar clubs, and all four oars are 3.5m long.

For long oar clubs the stroke is 4.0m long, and oars 1, 2 and 3 are 4.3m long. To allow oars 2 and 3 to be this short, the pins need to be mounted on blocks glued to the inside of the gunwale.

The dimensions at each station are the same, but the distance between each station is less for the shorter oars.

pastedGraphic.png

The inboard and outboard are joined with a 6:1 scarph, 270mm long. The scarph joint is cut so that the feather end of the outboard is at the top of the oar, and the feather end of the inboard is at the bottom of the oar.

The handle needs to be 400mm long, and around 40mm in diameter according to taste. A good section is oval 35mm deep and 40mm fore and aft, which allows smaller hands to grip but keeps more strength. It is sensible to make a gradual transition to the rectangular section for rowers’ comfort and to reduce stress concentrations.

Varnish or paint the oar well, as the additional weight is less than the weight of moisture soaked up by an inadequate paint job.

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Summer 2017

Outings are routinely scheduled, by request, for Fridays at 1800, and Sundays at 1400, although of course folk can row at any time. The midweek afternoon outings have been abandoned as it is always very difficult to get enough folk interested. Should we continue to have fixed times, or should it always be ad hoc?

The routine is that the first one to pop their name up emails members 24 hours before the proposed outing, should there be a gap in the crew. Sue puts up the post, on the ‘Book A Rowing Session‘ each week, but this does not necessarily mean that she is free to row, unless she puts her name down of course! Occasionally, more exciting opportunities are also advertised on our facebook page.

Just to whet your appetite:

Sunday 14 May Glencoe
Melfort Muster 27 May
Loch Sunart Raid, 10/11 June
Iona Regatta, 28-30 July
CASTLE TO CRANE, 23 September (Clyde)
Tay Row, on a date (midweek) to be confirmed by Seil members.

Sign up on the Book a Rowing Session tab!

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Talking about Oars


 

I hope that this post won’t be too technical, but at least it could provide something to talk about if anyone is out on a first date in Anstruther, North Berwick or Ullapool, where oars are the talk of the steamie.

 

At the last AGM the membership of SCRA approved a motion to set up a group of builders and trial rowers with a view to moving towards a standard oar that perhaps might at some distant future date become compulsory for use in racing. Because people are fond of their individual designs and skiffies tend to cherish the slightly anarchic nature of coastal rowing the latter was maybe only a remote possibility.

 

The group recently reported and SCRA has now decided to recognise the general feeling against compulsion, with the result that two choices are now offered to clubs for each of oar length, construction, type of blade and oarlock system. Clubs are now invited to offer to make a new set of oars incorporating these variations and allow members from other clubs to visit and try them out.

 

Our club had already decided to make a new set of oars and been accepted as a “testing” club, so we can now go ahead.

 

Every one of the recommendations would produce a significant improvement in terms of efficiency and comfort over what most clubs have been using.

 

Regarding length, some clubs are sold on short oars and the recommendation would be for these to be 3.5 metres, which happens to be the length of our existing oars.

 

Longer oars would be 4.3 metres, 14 feet 1 ½ inches, which is a bit shorter than what some have been using, but gaining efficiency by positioning the pins on the inboard side of the gunwale by about 70 mm. In this event the stroke oar would be 4 metres, a foot shorter. Avoiding the extreme lengths in excess of fifteen feet, that some clubs have gone for, keeps the oars manageable and reasonably light.

 

Your committee feel that we should go for the longer length.

 

Regarding construction, the choices are an all softwood oar or a mix of softwood outboard and hardwood inboard. The latter is what we already use and produces oars that are better balanced and that would be our choice.

 

Blades can be flat or spooned, in the latter case to a specified design. Spoon blades seem to be more efficient, in that they scoop and hold water better, but this comes at the cost of being a bit more difficult to use, because you have to learn to lift them at the end of each stroke to avoid catching a crab! Because we row so often with relatively inexperienced people it seems better to stick with the flat blades we are used to.

 

Finally, regarding oarlock systems, the choices are between an improved version of what we already use, giving a more positive entry angle to the blade and better control, or an innovative new idea, with the oar slotting over a special pin with a round top. In either case the pin will be made from a tough acetal, rather than oak, greatly reducing friction. Our idea would be to stick with what we are used to and benefit from the acetal pin.

 

The plan is to go ahead with oar workshops as soon as we have acquired the timber needed. The sketch shows the basic design that we will be working to.

 

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Tay Row

We have been invited by Broughty Ferry for a social row up to the Tay Railway Bridge. They will provide a Cox and a boat, and we would row in company. They have given various weekday options with good tides to help us on our way. accommodation could be provided. Anyone fancying a trip away, please contact Sue and we’ll sort a mutually suitable date. We would host them back here on a reciprocal visit.

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Winter Maintenance

Selkie is upside down in Allan & Fiona’s garage behind Teddy’s Pond. We are planning to meet on Wednesdays and Sundays at 1400, normal winter rowing times. However, extra help outside these hours would be most appreciated. Phone 545 to discuss!

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REMINDER

For information:
(taken from the membership form)

Coxes/organisers for a rowing session should:
• Look up a weather forecast
• Check the tide
• Tell someone, who is not going out, when you expect to return
• Ring/tell this person you are safely back
• Check the boat equipment before going out
• Report any damage or missing items to a committee member
• Please treat Selkie and her equipment as though you, and friends of yours, had spent hundreds of hours making and painting her
• Everyone to wear a lifejacket onboard
• Make sure that at least one of the crew knows how use the VHF radio

To become an ‘approved cox’ (if you havn’t been on an SCRA coxing course), you should come out with an experienced cox (who can either be sitting in the passenger seat or rowing) to make sure that you know the ropes. Its good for everyone to take a turn in case the cox is taken ill; plus it gives a whole new dimension to rowing for you. Coxes need lots of extra clothes (and/or a dog) ru8v7q9.

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AGM 5 December 1830 @ Tigh an Truish

The 4th Annual General Meeting will be held in the back room at the pub, starting at 1830, on Monday 5 December. The pub closes at 2000, so no chance to enter into long discussions about oars (on this occasion, anyway!) Items for AOCB to Sue asap please.

AGENDA

1. Apologies
2. Draft minutes of the 2015 AGM
3. Matters arising
4. Convenor’s report
5. Treasurer’s report
6. Setting of membership fees for 2017
7. Election of officers and management committee
8. Winter maintenance
9. Regattas and events for 2017
10.AOCB

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Sweatshirts & Hoodies

If anyone else would like a hoodie or sweatshirt (as seen modelled by Sue on the facebook page and at outings since the Worlds) please let Sue know by Wednesday 28th. Sorry, I am unable to add photos to these posts on the web for some reason.

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Safety Briefing

Please see the attached safety briefing, following recent capsize incidents with a skiff, and a gig ‘down south.’

SCRA Safety Brief Issue 1 Summer 2016. Lots of learning points here!

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Scottish Water’s plans for Seil

Please see the unofficial minutes of the Stakeholder Group meeting, held on 6 June, concerning proposed changes to the sewerage system on the island. It might help determine where we go skiffing in the future!

stakeholder-papers 6Jun16

final minutes Stakeholder 6 June 16 v04

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