Building the Hull


The inner skin is on the mould, and the next stage is the foam.

The materials list for the shell is as follows.

Outer Skin 1 layer 300 g/m^2 E glass @ 45o; 2 layers 200 g/m^2.
Inner Skin 1 layer 300g/m^2 E glass @ 45o
Foam 10mm Divinycell H-80 bottom; 8mm H-80 topsides
Estimated weight of shell. 24 kg

The foam is grid scored around the bow sections to allow for the curvature - the skins are pretty severely 3-dimensional in this region. The reason for using a male mould with a ply skin is that all the skins & the foam can be vacuum bagged on, saving lots of resin & weight . ( perhaps 5-6 kg ) and no bubbles. It also means the foam/ hull can be faired up on a rigid base.- and makes building a second boat much easier should anyone want one.

It occurs to me that I haven't actually documented how this thing is getting built. I'm not doing the whole thing myself - apart from anything else I don't have the time. What's happening is that Bloodaxe Boats are making the jig and the shell, and I will do all the fiddly bits and the fitting out. Quite where the break will come depends a lot on how the wallet stands up, but Bloodaxe will be doing at least the main shell and the false floor, not to mention - of course - the daggerboard. The rudder will be the Bloodaxe foil off my Cherub - I don't think I'll be able to sail both at the same time! This is quite a nice split, since the big parts of the job are pretty challenging for someone like me who doesn't work professionally with composites, but quick and straightforward for the pro, and all the little fiddly bits of fitting out, brackets for cleats etc. are horribly time consuming for a pro, but quite easy for me to do an hour or two on in the evening after work.

It strikes me as exceedingly handy that the Bloodaxe should have got an email account just before this project started. We seem to have done 90% of the planning and design process by email They can't be held responsible for the hull shape or concept - I suspect Andy Paterson would have drawn something rather different - but have had an enormous influence on the details of construction and materials, and in fact in making the whole thing a practical proposition.


In a short delay waiting for the foam to be delivered Bloodaxe have started on the daggerboard. Its Cedar core coated in unidirectional glass in three tapered layers, vacuum bagged for strength and (less) weight. The projected finished weight is about 2.2 kg ( lighter than a 470 rudder blade and 50% bigger). (End of Bloodaxe commercial :-) ). Seriously though that construction can be regarded as mid-tech, which is more or less the theme of the whole construction. In general I've stepped back from the leading edge a bit, as much as anything else for reasons of cost. Amusingly enough the materials are pretty much the same as on my Cherub, built 1979/80, which was much less compromised for cost…


"Foam is stuck on the bottom and flares, and the topsides will go on tomorrow, so with a bit of filling & fairing the rest of this week, the [outer] skin should be on next week, and then off the mould!" [Extract from Email message].


The outer skin is on today . The final layup was the +-45o 300g/m^2 glass with a single layer of 300g/m^2 0o/90o E-glass instead of two layers of 200g. This was after talking to SP, but it also saves lots of time with one extra layer instead of two. There's unidirectional carbon along the gunwale edge, because this is the main longitudinal member in the absence of the box section formed by conventional side tanks.
Andy has some photos of the boat at this stage, so as soon as he can get prints to me so I can scan them they'll make an appearance.
Next is to make a cradle, and remove the shell from the mould. The peel ply will be left on until the filling/fairing happens, ( best when the edges/decks are done.) as it helps keep the hull clean.
Once the shell is out of the mould I can get a good luck at what the boat will look like to sail in for the first time, and it will be time to make some firm decisions about the interior layout. First thoughts on this topic are on the Hull Design page.

9/10/1997 (evening)

"The shell is done! :-)
And off the mould . Weight is 27.5 kg (oops ) but this includes ~1.5kg of peel ply and the edges are not trimmed. So wt is 25.5kg ish. ( also inc. foam gunwales + carbon ). The weight is usually more than the estimate!"
[Extract from email message]


I went down to the Island last Wednesday (15th October) to pick up the mould (I'm going to store it for a while in case anyone else wants one) and to make decisions about the internal layout. Unfortunately I forgot to bring a camera, and so there are no new photographs. The internal layout will be the simplest. A false floor running from transom to bow, running from the join with the flares and dished in the middle, about 260mm in way of the centreboard case, and about 25 mm at the transom. There will be a low raised triangular brace for the daggerboard case, and a front bulkhead and foredeck. The foredeck runs out across the flare, and this forms a box section for the main rig loads. The daggerboard works out amazingly far aft when you are used to two handed boats, and accordingly it looks as if I shall be building a rudder gantry to give a bit more leverage and control for the rudder.
I'm really happy with the look of the boat thus far, it looks sleek, quick and radical. Judging by the interior layout Andy mocked up out of cardboard there will also be about enough room inside for a family of four to have a picnic! I only hope it looks as clean and neat with all the bits on. The other, increasing, concern is actually sailing the thing! Its going to be, in certain conditions, a substantial boat handling challenge, and in some ways will be appreciably trickier to sail than a Cherub. The bigger rig, which will make it overpowered a lot of the time will certainly add to the challenge. On the other hand there's no way it will be as difficult to sail as an International Moth, although that's not necessarily that encouraging!


Andy has been making progress on the false floor and bulkheads. These fiddly jobs always take more time than you'd think compared to the main hull. He elected to make a jig for the false floor and vacuum bag it. This saves weight and adds strength against the usual thing of glassing one side and dropping it on top of the bulkheads, but requires better planning and measurement. Its more convenient and less hassle for the pro, but I have my doubts as to whether it would be the right call for an amateur building their first boat. All the main bulkheads and so on are made, its just (just!) a question of fitting them in now.


I've just been down to pick up the bits and pieces to make the wings. For various reasons I had to go down by public transport and via a shop in a town some way off the route. The eventual journey ran to 8 train rides, 3 bus rides, and a return trip on the hydrofoil! The look on some of the various transport staffs' faces when greeted with a passenger carrying a 8 foot by three foot parcel of bits of boat as hand luggage was also entertaining!
Anyway, the false floor is in, and the whole thing is making excellent progress. I think it will probably be at the stage where I will be taking delivery of the part-complete hull to finish around Christmas time. I have to admit that I'm mightily impressed - and also a little daunted - at the standard of work that Andy Paterson has done on this boat. Its going to take a lot of effort on my part to get anywhere near it, even without time constraints. As to when I finish it - well, I've always said that my target is to be on the water by September!
The next stage, of course, will be the mast…


[Email message]
"I'm racing ahead now.... foredeck on, glass tomorrow, tunnel on and glassed today. I've fitted the c/case at the back of the slot, and filled the front with the 30mm foam, and glassed over. ( parcel tape + wax on top surfaces, so inners not bonded to top skin). Cut top and bottom glass skins in board shape to fit board. If you need to adjust position, will have to cut away top skin ( ie open the slot,) remove foam, slice as reqd, and refit in new position. ( and glass over to hold every thing in ) But the board should be in the right place for the first rig if its raked right. ( ie lots! )"
The reference to the daggerboard case is part of the change proofing I'm trying to build into the boat. If it ever gets a jib, or some other radical change in the rig then the board position might need changing. If its solidly located in position then this would mean major surgery. Consequently the dagger board case itself is getting on for two feet long, but the daggerboard itself fits into a sort of "cassette", which, if the need arises, could be moved forwards as described without too much drastic surgery.


Picked up the hull from Bloodaxe today. Not the day to do it - it snowed today. You have to understand the English attitude to snow to understand why this is an issue - as the late great Sandy Denny wrote "They said that it was snowing/in astounded tones upon the news/I wonder why they're always so surprised/'cause every year it snows". Anyway English roads descend into chaos - it took 45 minutes to get off the car ferry onto the Island because all the artics (semi-trucks to you Americans) were getting halfway up the hill out of the ferry port and sliding back down again. We wrapped the boat up in polythene sheet with lots of parcel tape and I headed back. At Portsmouth I stopped to buy more parcel tape and wrap it up again - properly this time! Anyway, time I got down to some work. Trouble is the list of domestic jobs that "you've got to do before you start on that d*** boat" seems to have increased rapidly.
While I was in Cowes we stopped off to look at Avenger, Uffa Fox' revolutionary International 14 from 1927, generally regarded as the first planing dinghy. She's on display in Cowes Library, and well worth a visit. Its interesting to note how hull shapes have evolved from what was most definitely the state of the art 14 footer 70 years ago, to what I would like to think is a state of the art 14 footer now. The first thing that strikes you is how full the bows are. Even though the design waterline seems to have had a straight entry this is partially because there is so much rocker forward. Having said that though I think its likely that the bows have distorted over the years - there's a sort of knuckle in the section that is absent from all the drawings of 1930s Fox 14s that I've seen. Amusingly the knuckle makes the bow section look something like that on Andy Paterson's most recent Cherub design! The other big differences are that there is so much more rocker, the waterplane is distributed more towards the centre, and the transom is narrower.
The other thing that strikes you is how incredibly complex - and presumably expensive - these boats must have been to build. She's planked over what must be hundreds of tiny - ½ inch by ¼ inch ribs, and below the waterline there is a transverse plank between each rib - thus running at 90 degrees to the main planking. All is fastened with tiny nails, clenched on the inside. Still, I guess it was worth it - Uffa is in print as saying that Avenger's hull as built weighed 190lbs, and there are all too many classes that make that look light even today with the incredible advances in materials.
I was once privileged to meet a gentleman who had crewed in Avenger, at the UK Dinghy show some years back. He was a kind of guest of honour of the RYA. Anyway it seems that age had done nothing to reduce his concept of what a boat should be like. I was on the Cherub stand, and I seem to remember a conversation that went something like "All these boats - far to d*** heavy. How much does this one weigh? 110lbs? That's more like it." Its all too easy to forget that the people who were involved with these historic boats were probably far more innovative and dismissive of "Its always been done that way" than many of us in the true development classes are now!


This has been the first day I've really seen some progress, what with Christmas and the requirements of the rest of the household to box in pipes in the kitchen and build gates to keep dogs out of certain rooms.... I made up the basics of the wing beams yesterday - a block of 30mm foam with a layer of 200g carbon then a layer of 200g glass on each side, and then cut out the actual beams from that and shaped them up properly. The laminate will provide the sides of the beam, which are not that heavily loaded - the real load will come top and bottom where there will be several layers of carbon. I got some peel ply with the "bits" kit from Bloodaxe, which I've used for the first time, and I must say it eases the job considerably.
Today I glued the beams on the wing panels which Bloodaxe vacuum bagged for me, and have made up some right angle section carbon beam which will provide the brackets for the wing pivots. This is curing as I speak much compressed with clamps and B&D Workmate in order to get as good a resin ratio as possible. You don't need a great many tools to build foam boats, but an almost inexhaustible supply of G cramps is just as useful as it is for a wood boat. Apart from that the main tools I seem to use are surforms, various power sanders, a Stanley knife and a jig saw. Oh, and most important of all, an electric fan heater to keep the temperature up.


The trouble with all these little jobs is that you spend an hour or so doing some work, then have to stop for the day while it all cures. I'm currently making up the wing beams, with unidirectional carbon on the top of each beam to take the main tension loads. Three tops completed so far, the next should be tomorrow. The tops of the wings are having about 6 layers of unidirectional carbon - it actually varies between 4 and 6 across the beam due to the width of the unidirectional carbon tape. There'll probably be only four layers on the bottom since the loads should be less.
Spent some of the spare time today drawing up the boat a bit more. This drawing should be clickable for enlargements.
Drawing of Boat
And if your browser doesn't support that type of image map or I've got it wrong, here are direct links!

Top View Side View End View


The heater in the garage broke down today. It was a little electric fan heater I bought when I was building my last boat. With all the epoxy and glass dust that must have been through it I guess I can't complain too much. Fortunately I was working on a small piece that could be wrapped in plastic and brought in the house to cure, otherwise it might have been pretty awkward. My advice is *now* that you should always have an alternative source of heat in case of failure if you're working in the winter...
This morning sailing at my Club got called off - forecasts of 80mph gusts... It was certainly pretty unpleasant when I got there, but I was ready to take the boat out. However it seems I'm the only one in the Club who has an old mainsail with points for a couple of slab reefs put in!


Its been pretty slow progress the last ten days. Unfortunately the need to work in order to pay for the boat has got in the way! I lost all last weekend and a lot of evenings - I'm having to build a new external email gateway for the organisation in a bit of a hurry! The evenings are a particular nuisance because I have to make a pretty early start if (as the domestic authority insists) I am to turn the electric heater off overnight. The wing beams continue, but they do now all have their main structural carbon on (the last two are curing in the garage as I write. The brackets and hinge points for the wings will be next, which is one of the more obvious potential failure points. Right now I'm off to mix up a good size batch of filler and coat all the wing surfaces ready for final smoothing...

Wing Construction Details

So why are the wings hinged anyway?
Less hassle when the boat's being towed.
In order to fit through the security gates between the dinghy park and the water at my Sailing Club!
 End Elevation
Reinforcement (thick black)
4 layers * 200 gsm carbon cloth plus two layers 400gsm biaxial glass cloth (6* carbon on top surface of beam)
8mm 80gsm foam (blue)
Beam foam is similar density (red)
General layup - two layers 200gsm cloth on top surface, 1 layer on bottom

Side Elevation
Blue dotted line is radius of clear area for pivoting
Bearing tube is between existing main skins, end skin is
added afterwards.
Dig out foam from end of beam to level with outboard face of pivot, replace with filler then add carbon round radius end (4 layers?) Also wrap 2 layers of carbon right round beam laterally.
Make sure there's adequate reinforcement under the bearing area of the wing bracket to distribute loads evenly. Carbon/glass tapered thickness patch probably best.


A Minor milestone reached tonight I think - I've just glued in the bearing surfaces in the wing beams. There's still a lot of odds and bits to do round the beams, ensuring all the surfaces are covered, filling in round the pivot points, a little bit of local reinforcement and some trimming to make sure they pivot freely, but basically that part of the job is rapidly approaching completion.
Last Saturday, with the first of the wing brackets in position, I took advantage of a dry day to take the boat outside and get some photographs from different angles. These will appear at the end of the next batch of film, probably another week or so. I've also started on the rudder and tiller, which will be a daggerboard affair utilising my Cherub rudder blade. The core is all done now, its a matter of laminating up the fibres and the final assembly. The next job after the wings will probably be to construct the rudder gantry. The other big job, which I must confess I'm putting off, is the edges of the wings. The inner edge just needs a glass tape capping, but the outer edge needs a fairly solid beam. In addition this beam will be what I end up sitting on, so I really ought to make it nice and wide for comfort. The last jobs will be fitting out, rigging - I'm going to make the boom from an old Needlespar wing mast I have lying around, whilst Bloodaxe are currently looking at options for the mast, and painting. I'd really like to get the paint done professionally - its not a great talent of mine, but of course its shaping up to be exactly the wrong time of year for that. Fitting out doesn't look to be too onerous a job - one of the lesser advantages of a single sail rig I suppose -with the exception of the toe straps, which are going to be a nuisance to get a decent anchorage for.


Lots of work over the last few weeks, but its all little bits and bobs that don't show up well in pictures. I've also lost a few shots with some kind of developing or camera fault which is annoying. The wing mountings are complete, I've more or less finished filling and tidying up round them, and am now well into building the rudder gantry and the rudder stock. There's another delay coming up though, because its the UK dinghy show soon, and I'll be putting together some material for the Cherub Class stand. The promised "outside" pics are now up on the Picture Gallery page. I've just ordered the mast and all the gear - this latter is quite a substantial hit in spite of the fitout being fairly modest. Maybe the real reason why Lasers aren't allowed proper blocks and have all those loops and eyes is to save 50 quid off the suppliers costs:-). I've also updated the graphic further down this page. The rig is more accurate I think, and the drawings are bigger.


All these little jobs seem to take more time than you can possibly believe... I knew that I suppose, but you never quite remember. The gantry is complete now - I had to do some re-thinking round the transom because I failed to observe rule one of gantry design - make sure its attached to an extremely solid bit of the boat. Rather perversely I re-engineered the boat rather than the gantry, and there is now a three by one inch carbon beam across the transom top from topside to topside... The rudder stock is very nearly finished, and seems to be bearably light. I've started gluing in the foot rails, and after those I think that the only structural job left will be putting in the mast step, which I may well leave until after the majority of the painting as it will have fittings on. Apart from that I need to put a few more holes through the flares for ropes, toe strap anchorages and such like, and then start fairing and painting. Andy had already done a lot of that, so its going to be mainly tidying up after the stuff I've put on - and desperately trying to tidy up my work so its not too glaringly obvious which bits I did and which bits are Bloodaxe's.


Still progressing slowly with all the little jobs. The first coat of paint is on the outside and (as of this morning) the decks too. The first coat of paint is really good for showing up all the deficiencies in the filling and fairing work, so no doubt there will be more of that. The foot rails in particular have been loads of hassle for that, partly because I didn't make too great a job of laminating the heavy bi-directional glass that covers the foam cores that they're based on. Should have some shots of the gantry and the interior with the toe rails in soon, assuming the photos I took yesterday come out.


Sanding Bloody Sanding (How Long, How long must we...). OK, that's enough of the rock music references. Actually Springsteen has featured high in the play list for this boat for some reason. Anyway, I digress. Lots of filling and so on. I brushed on a thinnish layer of filler on the bottom of the hull, and it still hasn't quite gone off two days later, so sanding it off is expensive in glasspaper. I've got the boat booked into a sprayshop for the 18th of May, so that's a pretty major target and project milestone. After that I have to fit the hull out and then its time to stuff the rig on.. As of Friday the mast hadn't yet got to Bloodaxe, but is promised for this week, and of course until we've had a good look at the mast there's not much that can be done towards the sail. There's some more thoughts on this on the Rig Design page.


The boat should go off to the Spray Shop tomorrow. Not really ready - had another panic weekend at work, but at least the overtime should pay for the extra work the painter will have to do... Bloodaxe have been doing some final work on the wings for me, but the mast *still* isn't with them, though it has *really really* been promised for this week. Reminds me of an old story - "the only boatbuilder who ever finished anything on time was Noah, and he was an amateur!" (Sorry Andy). Another delay is insurance - the insurance company want some kind of survey... Good grief!


The Mast has now been delivered to Bloodaxe, who are also doing some extra stuff on the wings and painting them, while the hull is at the local spray shop. The only bits with me right now are the rudder stock (1.1kg, but very strong, possibly overbuilt[1999 note - it wasn't - I broke it!]) and the mast step, which has a positive bush of Ronstan blocks sprouting on it. The light is beginning to appear at the end of the tunnel I think. Two small but tricky details to sort are Insurance - companies tend to look in askance at a non-class dinghy - and a cover for the boat, which could require a little more though than the usual restricted class measurement form!
I've decided on a name for the boat, it will be "Angua von Uberwald". She's a character in a series of books by a gentleman named Terry Pratchett. Most of my boats seem to get named after vaguely SF or Fantasy female characters of somewhat positive temperament (Halo Jones, Angelina deGriz) and this one can be variously:-

In short she's a were-wolf. Somehow it seemed appropriate...
All I need now is the foredeck art, she's supposed (in Wolf form which is what I'd want - I'm no fan of the hackneyed fantasy "All Boobs and Leather Accessories" style of artwork) to look something like a Wolf/Afghan Hound cross, which I actually find difficult to imagine, but then TP is a cat person... The foredeck will be International709 Lauderdale Blue ( a vaguely slightly greener than Royal blue sort of colour IMO), so I was thinking white lettering and white line art would look neat.


It was time to make some final decisions about the Rig today. Caws Sails, the sailmakers, have one of those "every job has a small hold on" slots in the schedule, so I needed to make my mind up fast to hit it.


The mast stump is well on the way at Bloodaxe. There are also spreaders and so on for the rig to do - lots of odd bits that I really ought to do myself, but I haven't had a lot to do with carbon rigs in the Cherubs so I'm steering clear of it a bit. The sail should be more or less complete by now at Caws. The boat isn't back from the spray shop yet - they had an outbreak of flu which has not done their scheduling *any* good at all. I've got insurance arranged now, so I can tow the boat back from the paint shop without my fingers crossed... In theory we should be just a few weeks away, but the last few "little" jobs have a habit of taking far longer than you could possibly believe...


Getting there slowly. Beware everyone, involved in similar project, these last stages seem to take enormous amounts of time! The boat is back from the spray shop, but its a bit of a disappointment. The finish isn't quite as good as I would expect a professional shop to achieve, although its was by no means top price, so I guess you get what you pay for. The big problem is my fault - I favour two colour paint jobs with two shades of blue fading into reach other with overspray. The only trouble is that the two shades I picked out are so close together that the effect is, to say the least, rather subtle... Of course they looked farther apart on the colour chart. Maybe next time.
Bloodaxe have the mast stump and other associated work largely complete. I've now got most of the fittings on the shell. The last couple of jobs have been to build the boom, which is cut down from an old Cherub wing mast. Its reasonably light, [1999 note - too light - I broke it!] and, more important has cost me very little money and cured the "how long is that thing going to be cluttering up the place?" domestic discussion! Next spar construction job is the prodder, and I'm currently undecided as to whether that should be carbon or aluminium.
The current job is to arrange breathers for the buoyancy tanks. Modern epoxy/foam sandwich boats are (or should be!) totally airtight. This can lead to appreciable build-up of air pressure from a cold morning to a baking hot afternoon, and the Moths (which are very lightly built of course) have taken to putting air breathers in the tanks to stop this happening, and I've done the same thing. The trick, of course, is to route them so that they don't let water in. I've chosen to locate the breather tubes primarily within the tanks rather than outside so that they can't get damaged, and all I've done is glued fine (4mm exterior diameter) flexible plastic tube in an appropriate route. All the other tanks vent via an inverted U shape tube into the left front tank, and that tank vents to the outside world via a run that starts just about on the floor at the centreline, and then runs up to the underside of the foredeck, and from there along the top of the foredeck and out through the front bulkhead near the gunwale. I hope I've got this right - the idea being that there is no situation in which the entire length of the tube is likely to be under water, and in any case the small diameter of the tube and the air pressure within the tank should prevent significant ingress.

July '98

Building The Mast Stump

Fitting out the mast stump was a lot of trouble. What Bloodaxe presented me with was a large carbon tube, with a couple of s/s rings bonded into the top for the lowers and a section of s/s track bonded on the front with carbon straps top and bottom, and filleted over the rest. They also gave me 4 pieces of solid carbon as bearing surfaces. My mission was to shape these to their precise shape and locate the inside the stump - the lower two some way down the spar. What I eventually did was to shape them so that they wound up with about a millimetre or two of clearance (somewhat less than a precise interference fit). I then covered the spar in parcel tape, located the bearing surfaces in place with plenty of candle wax to allow for my clearance, and finally put plenty more candle wax around the outside. I then slid things into place and located some holes for self tapping screws in each bearing from the outside of the stump. On with plenty of stiff epoxy (microfibres for strength, silica for viscosity), on both the bearings and in appropriate places inside the stump, and fitted the bearings - still waxed to the mast - in place. Now the self tapping screws went in, hopefully breaking the seal on the wax and giving the bearings full clearance and glued firmly to the inside of the stump. Once cured plenty of heat melted out the wax and I was (just) able to remove the parcel taped mast. Finally an improvised sanding tool (steel rod with a slot in the end and 200 grit sandpaper) was used to make sure that the mast slid freely up and down the stump. Marks out of ten for "fiddlyness" - about 12!
I made the prodder from some carbon tube that I had left over from other jobs. Its really too light, and it bends under heavy load, so may have to be reinforced at some time.

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