Build an Irish proa

Mike Teale de­signs and con­structs a small, sta­ble craft suit­able for solo mo­tor-cruis­ing on the Erne-Shan­non waterway sys­tem

Practical Boat Owner - - Contents -

A small, sta­ble craft suit­able for solo mo­tor-cruis­ing

One of my many res­o­lu­tions when mov­ing to Ire­land in 2015 was that my habit of build­ing rather strange, small boats ev­ery year or so was at an end.

How­ever, events took a turn, as they so of­ten do, and I felt it would be fool­ish not to use some free time to ex­plore the Shan­non-Erne waterway. In or­der to that, I would re­quire some sort of craft and, while a hire-cruiser may have rep­re­sented the ob­vi­ous an­swer, it seemed a shame not to build some­thing and try it out.

For some time I had mulled over a method of build­ing a small boat with ad­e­quate ac­com­mo­da­tion for one per­son who is used to, and en­joys, camp­ing. The prob­lem es­sen­tially re­volved around pro­vid­ing an en­closed space around 0.65m wide by 2m long with a head­room of about 1.2m and incorporating it into a boat form that was sim­ple and fast to build, very sta­ble, light, shal­low draught and rea­son­ably ef­fi­cient to pro­pel.

The con­clu­sion that I came to was that a proa con­fig­u­ra­tion (or, more cor­rectly, an outrig­ger ca­noe) would pro­vide the eas­i­est so­lu­tion; a slim cen­tral hull pro­vid­ing the ac­com­mo­da­tion with sta­bil­ity pro­vided by an even slim­mer pod con­nected by cross­beams. Propul­sion would be pro­vided by a small four-stroke out­board. As such an­i­mals are sur­pris­ingly heavy when com­pared to their two-stroke pre­de­ces­sors, I would mount it cen­trally to keep the ends of the craft as light as pos­si­ble. The only real con­cern I had was whether the out­board would sim­ply push the boat round in a slow cir­cle ir­re­spec­tive of what the rud­der did. If this ac­tu­ally hap­pened, Plan B would be to mount it on the aft bulk­head and form a well and, of course, pre­tend that this had been the idea all along.

The ‘flat bot­tom and box-sides’ ap­proach is a bit of an eye­brow-lifter to those whose con­cept of a proper boat has silky curves at its core, but the flat bot­tom al­lowed all in­ter­nal space to be use­ful while keep­ing draught to a min­i­mum and en­sur­ing that build­ing dif­fi­culty was ‘ex­ceed­ingly lim­ited’. A sim­ple sketch was the ex­tent of my de­sign aside from con­vinc­ing my­self, via ba­sic cal­cu­la­tion, that when fully loaded with the 75kg de­signer/ con­struc­tor, 20kg out­board, 15kg fuel, 10kg of sleep­ing bag and associated items, 5kg of food and 10kg of the vi­tally im­por­tant ‘mis­cel­la­neous’, I would be left with rea­son­able free­board.

Ma­te­ri­als

Ply­wood was the ob­vi­ous ma­te­rial of choice, and I went through the usual is­sues when try­ing to source ma­te­rial that was good enough for the task with­out be­ing ridicu­lously ex­pen­sive. Ply­wood clas­si­fi­ca­tions used to be pretty straight­for­ward but, these days, it is dif­fi­cult to know what your money is buy­ing. Indeed, in the end I pur­chased what seemed to be rea­son­ably-priced marine ply­wood, but the de­liv­ery docket stated ‘Marine ply­wood to BS1088 (not for marine use)’. Cu­ri­ous.

I used 6mm thick­ness for ev­ery­thing apart from the bot­tom and bulk­heads of both the pod and the main hull, which were 9mm. Con­nec­tion ar­eas for the cross­beams to the bulk­heads were dou­bled-up 9mm ply­wood, and other

items were made from tim­ber which was ly­ing around. I used a com­bi­na­tion of screws and epoxy and all sig­nif­i­cant ply­wood-ply­wood seams were also taped with glass­fi­bre and ended up with a struc­ture that was strong, rigid, rel­a­tively light and wa­ter­tight (in terms of both lake and rain wa­ter).

Paint sys­tem

In or­der to pro­tect the ply­wood that would be ei­ther un­der­wa­ter or close to that re­gion I ap­plied a con­ven­tional oil-based ex­ter­nal paint sys­tem of primer, un­der­coat and two coats of topcoat, and then an ad­di­tional two coats of wa­ter­proof bi­tu­men paint. I was a lit­tle un­cer­tain re­gard­ing this ap­proach as I had not tried it be­fore, so I con­tacted the man­u­fac­turer of the bi­tu­men to seek their ad­vice, by email. I re­ceived a re­sponse which was not par­tic­u­larly use­ful as it ducked the ques­tion of whether their paint could ad­versely af­fect the un­der­ly­ing paint sys­tem by, for in­stance, soft­en­ing it.

To bol­ster my con­fi­dence I cre­ated a small test panel, and the re­sults seemed to in­di­cate that in the short term at least, nei­ther paint sys­tem had any ef­fect on the other. In­ter­est­ingly, dur­ing my sub­se­quent trip I was chat­ting to the own­ers of a wooden boat built in the ’30s that was used for day-trips on the Shan­non, and they told me that the ap­proach I had adopted was very sim­i­lar to one that they had used suc­cess­fully for many years. Noth­ing, as they say, is new.

Con­struc­tion

The con­struc­tion process was very straight­for­ward, and us­ing only very ba­sic tools and not a great deal of fo­cus, ev­ery­thing was com­plete and ready to launch in less than 8 weeks (prob­a­bly 250-300 hours). I kept to the key di­men­sions on my sketch but the ex­act curve of the hulls in plan and sheer was merely ‘pleas­ing to the eye’ as op­posed to any­thing more ex­act. The main se­quence of events was to join 8ft lengths of 9mm ply­wood for the bot­tom of the main hull and the 6mm ply­wood for the sides us­ing epox­ied butt-straps, cut them to shape, fix the chine piece to the bot­tom, fix the sides to the chine, cut out and fix the bulk­heads, fix the top stringer, fix the hor­i­zon­tal cabin-widen­ing piece, fix the cabin and decks and then fit the intermediate stringer.

Then I built the pod, us­ing a sin­gle length of ply­wood, and fi­nally I cre­ated the cross­beams. In hind­sight, the only dif­fer­ence to this ap­proach that would have been ben­e­fi­cial would be to have built and of­fered up the cross­beams to the main bulk­heads of both the main hull and pod be­fore fix­ing them.

In the event, the cross­beams re­quired var­i­ous shims and wash­ers for a good con­nec­tion to be made.

Launch day

Launch day ar­rived in mid-April, and my re­source­ful friend Wal­ter Quirke trans­ported the craft (bro­ken down into its com­po­nent parts) to Bal­lina on the south­ern part of the Shan­non River where there is an ex­cel­lent slip­way. To­gether, we as­sem­bled her, and off she floated with no nasty lit­tle leaks of any de­scrip­tion. There was great in­ter­est from passers-by, and a kayaker made the ob­ser­va­tion that, re­ally, she rep­re­sented an old man’s kayak with ac­com­mo­da­tion built-in and no need for phys­i­cal ef­fort to get from A to B. He was right. That is ex­actly what she is.

Over the next 18 days I made my way up to Belleek and back via Loughs Derg and Ree on the Shan­non, the Shan­non and Erne wa­ter­ways and then the Erne Up­per and Lower Loughs. Over­all, this trip is about 800km and must rep­re­sent one of the finest in­land wa­ter­ways voy­ages in the Bri­tish Isles, com­bin­ing se­ri­ous lumps of wa­ter with fetches of many miles and where sen­si­ble use of weather fore­casts and care­ful nav­i­ga­tion is a ne­ces­sity. One en­coun­ters the most beau­ti­ful of canals and rivers, where the ab­sence of boats out­side the main hol­i­day sea­son is re­mark­able, and the wildlife and scenery al­most over­whelm­ing.

Twill, as she was known (as in ‘it will do’), per­formed splen­didly in the mixed weather that I ex­pe­ri­enced. As with all craft, she had her own char­ac­ter­is­tics, and one was that when start­ing off from sta­tion­ary she would gen­tly turn to port un­til the speed was above about 1.5mph. How­ever, when com­ing into a moor­ing, with the en­gine in neu­tral, she would steer pos­i­tively right up to the last mo­ment.

I rou­tinely had the 3.5hp To­hatsu en­gine throt­tle at the po­si­tion marked ‘re-start’, and at this she trun­dled along at be­tween 4.0 and 4.3mph ac­cord­ing to GPS, de­pend­ing on wind di­rec­tion, and con­sumed 5lt of fuel ev­ery 11 hours. By open­ing up the throt­tle to about a third of max­i­mum, she moved at about 5.5mph but with a con­sid­er­able in­crease in wash (and noise). Us­ing more throt­tle than this caused in­ter­mit­tent pro­pel­ler ven­ti­la­tion which will prob­a­bly be over­come, or at least re­duced, in the fu­ture by low­er­ing the po­si­tion of the out­board such that the ven­ti­la­tion plate is a few inches un­der­wa­ter at rest.

The sleep­ing ac­com­mo­da­tion turned out to be nigh on per­fect, and I had 19 ex­cel­lent rests in the dry and warm. It ini­tially took about 30 min­utes to get all the gear in the right place and then get com­fort­able, but this re­duced to about 10 min­utes after ex­pe­ri­ence was gained and rain showers pro­vided a mo­ti­vat­ing force.

Sta­bil­ity, un­sur­pris­ingly, was ex­tremely good, so there was never any need to plan how to get on and off or where to sit when the wind howled. Lat­eral rock­ing mo­tion re­sult­ing from wave ac­tion was quick and jerky, as with all small mul­ti­hulls, but there was very lit­tle pitch­ing at all, mainly due to her very fine, un­flared bow.

The project was cer­tainly a suc­cess. It is al­ways sat­is­fy­ing to come up with an in­di­vid­ual so­lu­tion to a sit­u­a­tion and, for me, this lit­tle craft is great for easy ‘hik­ing on wa­ter’. She formed the ba­sis of many con­ver­sa­tions on my route and, while those used to large cruis­ers were aghast that I would sleep in her, those used to camp­ing were im­pressed at the space avail­able. It takes all sorts!

A sim­ple sketch was the ex­tent of my de­sign

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