1:28 J Class Enterprise - build log

Here we go!!

My first experience of the J class was in the early 1980’s when I went aboard Endeavour, at the time a rather sad but beautiful looking rusting hulk laid up ashore at Calshot, Southampton. She was owned and lived ‘aboard’ by a couple who my father knew, who were valiantly trying to restore her on a shoe-string budget. Needless to say, they were fighting an uphill battle and she eventually ended up being owned by Elizabeth Meyer. The rest, as the saying goes, is history.

As with most people the idea of building a model J appealed at every level, the bigest problem though was aquiring a usable set of line drawings. Unfortunately I possess neither a steady hand or sufficient computer skills to manipulate the somewhat hazy and faded images that I found in various books. Google to the rescue! Thankfully I came across this site and Claudio’s excellent drawings which included the required additional draft to produce a model that stood some chance of sailing like the original - research generally showed that a directly scaled down hull with additional fin and bulb for a better righting moment wouldn’t allow the scale sailing look of a ‘J’.

Anyway, onto the interesting stuff.

The intention is to follow Claudio’s methods for the build, that is to produce a planked male plug with a view to making a ‘female’ hull in fibreglass, although I’m hoping to produce the hull as a single moulding - the tumblehome doesn’t appear to be too severe and the relatively light layup should allow sufficent flexibilty to remove it from the plug - fingers crossed & time will tell!

As with many on these forum, I owe a huge debt of gratitude to Claudio for his time and skill in producing these particular drawings and for making them freely available, so thank you.

I’ll kick off with a few pictures to wet the appetite and then add others as time and progress permit.



Gidday ROW, I have these plans from Claudio as well and hope when I gathered enough building skills I’d like to tackle this beauty as well, so you have a avid follower on board.

I’m also interested to hear if any one who has completed boat from these plans ? nice to hear how she handles.

Oh one small request, is it possible to have larger pics ? the last two above seem to be postage size and hard to see any detail :rolleyes:

Cheers Alan

Thank you Row, for choosing my Jclass Plans for Enterprise.
Whish to see the follow up !

Hi Row
That keel could make it a real SOB to release in one piece. A thought or two. If you lay it up with no transom(add it later) it will be easier to release. Same with the bow if possible. If you don’t already know, compressed air is a big help in loosening hulls. Just loosen the edge and blast it with about 90 psi. Take it to a local shop if you don’t have a compressor. You can also drill a small hole in the bottom of the keel in the plug so you can blast air in from there. If worse comes to worst you can take the plug out in small pieces(don’t ask why I know that)

Laminating the hull directly on the plug may reserve some difficulties to remove it after polymerisation.
In my discussion from page 3 onward :


I was suggesting the use of a wedges ‘alluminium sheet’ and laminate one half only.
Later, after removal of edges, use the 1st half as counter part support to laminate the second half.
See further explanations in the above tread.

Good evening gentlemen & many thanks for your support and comments.

K1W120 - Having seen and admired your skills in the AC120 thread my advice would be to give the J a go. I think I’m reasonably practical (I’ve owned and maintained ‘full size’ yachts for many years until recently) but I’ve never molded a model yacht hull before, so you’re already ahead of me there.

Don - agree with you 100% about getting the keel off the plug, it has the potential to be disastrous. What I’m thinking at the moment is trying out K1W120’s suggestion in Claudio’s Enterprise build log (3rd page post 21) and leaving the back face of the keel open to enable long thin blades to be introduced to assist separation. I think Claudio also mentioned this in one of his posts aswell. I’ve got a bit of time before I get to that stage so we’ll see how it goes - I may yet do it in two halves.

Claudio - really appreciate your feedback on this build. I don’t know how many times I’ve read your own Enterprise thread, I may even have it word perfect by now!! I will definately be taking onboard your comments regarding hull removal from plug and may well follow your methods completely - nothing is definate yet. I suppose my own thoughts were that having put so much work into the filling and fairing it would be a shame to have to build in two halves and then join them together. I was planning on plenty of wax layers on the plug and using PVA mould release to ensure nothing would stick. Maybe I’ll be rethinking that one.

I’ve noticed in various build logs that people tend to give their plugs the wax treatment but not PVA aswell and was wondering if there was any particular reason for that? Unfortunately I can’t find it at the moment but I read an article recently that said even professionals have problems with moulds sticking (especially new unbroken-in moulds) with a failure rate of approx 13 - 15% .

More pictures in the next day or so and sorry about the diminutive size of the last 2, I probably pressed the wrong button!



PS - In the manage attachments box (for pictures etc) how the **** are you supposed to delete pics from the upper box? Taken me long enough to work out how to put 'em there & now I’ve got all sorts that I don’t want!!

How to remove an already loaded image

About PVA, personnally I never used.
With 7 layers of wax I never got problems.
I never used a pretreated surface with polyurethane paints because most of waxes are not compatibles.

On the market, nevetheless, are available waxes fully compatibles with polyurethane surface treatment.

[QUOTE=Twister;60618]I’ve noticed in various build logs that people tend to give their plugs the wax treatment but not PVA aswell and was wondering if there was any particular reason for that? Unfortunately I can’t find it at the moment but I read an article recently that said even professionals have problems with moulds sticking (especially new unbroken-in moulds) with a failure rate of approx 13 - 15% .QUOTE]

Interesting point, I had used only wax in the past and it works well using plastic wedges for seperation together with compressed air gun, then I tried PVA release over the wax out of curiosity and found the hull just fell off the mould without any effort or need for using compressed air gun …hence I use PVA release as standard procedure now & it’s not expensive. :confused:

ROW I have two builds on the go now & reckoning J-Class will be my next project next winter.

Cheers Alan

Hi Alan, Just to let you and others know that the picture size is now fixed - as I thought, it was a small matter of clicking the wrong button - however, the 2 smaller pics are still there, I couldn’t find an obvious way of deleting them.

Also, interesting reading your comments about PVA. I spoke with a friend recently who’s in the boat building trade and he said that you only really need to use PVA on the first 1 or 2 hulls pulled from a mould although the surface finish of the moulded hull (ie the gelcoat) tends do be a little dulled as a resort. Obviously this then means that there’s a bit more surface finishing to do - for us not too bad, for him it means higher costs. Regarding yours and Dons comments about compressed air for releasing, like Claudio, I don’t have a compressor, but it is on the list of things that might be useful…



Many thanks for that Claudio, I’ll try and have a play around with the attachment stuff later on this evening to bring a little order to the photographs.

Unfortunately, no further progress today - my 22 month old son wanted to play and read hence next to no time in the workshop!



Additional question for you: I note (with thanks) your comments on release waxes & polyurethane paints. I’m planning on using acrylic primers & topcoats, are they compatible with the majority of waxes?

Sincerely I do not knows, but in principle should be written on the wax container.
If you are not sure , than make a trial on a little corner and after polymerisation try to remove the small lamination .
Generally this is the way I’m doing when not sure !

Claudio - I appreciate your honesty. Once I’ve got some release wax I’ll run a few tests to make sure they’re compatible.

A little more progress anyway, planking is finished and bow & stern blocks have been roughly fitted. The bow block was cut from a single solid piece as a sort of elongated pyramid and purposely left over size to enable final fitting etc by sanding. I should of pointed out in the first post that the planking is Douglas Fir. There was no particular reason behind the choice other than that I had several 6" x 2" X 6’ lengths in the workshop which could easily be resawn through my bandsaw.

Anyway, a couple more pictures showing bow & stern blocks being glued into position.

Hi Alan,

Just out of interest, what do you use for applying the PVA?

I know that in commercial applications it’s sprayed on, but I’ve also recently read that it can be applied with a sponge, brush or lint free cloth at a push - I’d welcome your thoughts.



Spray, cloth, sponge and brush. in that order would be my best guess.

Hi Row, I use high density sponge, pour genrous amount PVA realease over the surface and gently spread it with the sponge so has nice even thin coating, then just leave it to dry and laminate.

Noted the comment from the professional boat builder saying it dulls the surface, I actually had the opposite effect as the inner side of hull (male mould) was too glossy, had to sand areas where need to bond fittings, would like to try rip-ply for better bonding surface, but need to test if it works first.

Cheers Alan

Cheers Alan

OK guys it’s official - I really do hate long-boarding!!

Although it’s physically much more demanding doing it on a full sized boat (we used to call it ‘torture boarding’), in many respects it’s also alot easier - for one thing the curves are far more gentle.

Having said all that it was completely my own fault. I obviously got far too carried away with the initial sanding and ended up with fairly noticable flat spots and almost completely lost the shape in some areas at the turn of the bilge into the keel. It all looked & felt so good until the first coat of primer was sprayed on!!

Anyway, the beauty of using polyester bodyfiller is that it can be sanded after 25 minutes - try doing that with WEST epoxy and glass balls! Anyway, a combination of building up layers of filler and sanding/fairing between coats has now got the shape back to as it should be with the hull now finished in white primer (it was on offer at the local shop). I’m considering going over it again with a grey acrylic primer as I think it’ll be easier to see the dry glass cloth when I come to put a layer over the plug before wet sanding commences - any thoughts?

Having said that, I was wondering how necessary it was to give the plug a layer of glass at this stage - the hull is incredibly stiff and at the moment looks like a scratched gel coat finish. I’d certainly welcome any comments about this.

I need to sort a few things out on my camera (charge the battery, try and remember how to set the date etc etc, its a Nikon D90 if anyone knows, it’ll save me having to find the manual!!) and then I’ll attach some more pictures to this post.



PS. This bit’s for Alan really, I was wondering if you’d experimented with empty household trigger spray bottles for applying PVA or if you’d just gone with the sponge from the beginning. Also, which may sound ridiculous, but could you post up a picture of the sponge you use, its just that ‘high density’ is such a subjective term.

Camera sorted!

First three pics show (in order hopefully) the sanded hull and then two shots with first coat of primer, followed by re-primed after further filling & fairing, as is today after more f&f and finally the last shot shows how the hull is being supported for these various tasks - makes it very easy to angle hull for better access etc.

Hi Row, The PVA release has higher viscosity than water (in the area of sewing machine oil) and does not spray too well, more spits than sprays, hence I just used sponge to wipe it on, it was much faster and easier to get even coating.

Well now my wife thinks we have really lost our mabels, posting pictures of sponges now :stuck_out_tongue: but women don’t understand how important these things are do they :lol:

Firstly here’s the place I buy all of my materails from and you can see there comprehensive downploadable PDF to dribble over all the goodies they have http://shop.r-g.de/en/home/

Bummer about the flat spots, did give inside of the mould a couple coats of epoxy before started sanding ? have heard the planking can flex considerable with sanding causing this problem. Most definately laminate the outside of the mould and then give it coat of dark coloured paint to use as a tracer so you can see high low spots, being carefully of course not to sand through the laminate.

Cheers Alan

Cheers for the info Alan - my apologies for theft of marbles etc!!

The hull was given two coats of resin internally before any sanding was done although to be honest, having planked in douglas fir (fairly stiff timber) I don’t think it made the slightest difference to the structural properties of the hull. During planking all planks were glued to the frames and along each length where it butted up to its neighbour using a waterproof carpenters glue. Ithink the flat spots were really down to not concentrating properly which as I stated before, in extreme resulted in losing shape. My original of the first primer photo @ 10 Megapixels showed rather well the effect I managed to achieve!!

We live and learn - I certainly won’t be making the same mistake again. It’s these kind of mistakes that reinforce my admiration for what you guys are producing - especially looking at Claudio’s Enterprise, it’s not exactly an easy shape to work with.

Next stage will be the glassing of the plug which I’ll probably be starting sometime next week. Haven’t got any epoxy left at the moment, but I do have some polyester resin - would it be ok to use it for the plug glassing?



Just had a quick look at the website you mentioned - I wish I could get epoxy as cheap as that locally, I’m having to pay about £32 (sterling) for a kilo about 36/37 euros compared to 22! I may look into purchasing 3 or 5 KG packs to get decent savings.

I ran some tests with peel ply on some polyester/glass laminate and the results were pleasing. If I can find the samples I’ll post some pics later. Anyway, the sample without peel ply left a surface that looked and felt like the final layer of glass cloth. The sample with the peel ply applied when removed left a dull mat finish, ideal for bonding additional components to. I’d still be inclined to give the surface a light sand prior to bonding. Only issue that really needs resolving is peel plying the plug before laminating and achieving a smooth finish. Possibly would work using narrow strips of pp, say no more than 30-40mm wide. I’ll be experimenting with it inside the laminate on a future project - the shape of Enterprise doesn’t lend itself particularly to this potential method.

Anyway, if I can find the samples I’ll photograph and post them here later.



Picture added shows 2 samples, each is 4 layers of 175 g/m2 glass tape. The one on the right has been consolidated with a 1/2" brush. On left had a layer of peel ply over the 4 glass layers and was then ‘stippled’ until pp was wetted through. Peel ply was removed after approx 3 hours and I think the results rather speak for themselves. Bearing in mind I used polyester resin which I think usually leaves a waxy surface when cured, the pp’d sample showed no signs.

Where you can see the weave of the cloth on the left sample was from a very light sanding, just to satisfy myself as to the ease of cutting back the resin

Buer, buer, bu**er !!!

This is almost certainly a typical ‘newbie’ mistake, but having spent the last few days giving the drawings further study and preparing the hull for its glass sheathing I noticed that the sheer line from frame 10 to the transom didn’t look right. After much head scratching etc I realised that when I started to plank the hull I had lined up the outside face of the inwhale plank with the deck line. With most hulls this isn’t to much of a problem. However, with Enterprise the hull flattens out towards horizontal from frame 10 going aft. This has meant that when the hull plank was fitted, carefully lined up with the inwhale, the topedge of the outside face was now upwards of 2.5mm too low which gave the sheer line far too much upward curvature as it ran aft.

Hope that makes sense - unfortunately I don’t possess the computer skills of some on these forum to provide a diagram. My plan for fixing this is to clamp a plank to the outside of the hull with its inside top face aligned with the deck line and then to fill the gap with polyester filler. I’ll attach a couple of pictures to this post later by way of explanation.



I think the two pictures best demonstrate the problem and the solution. The plank clamped to the sheerline was wrapped in clingfilm (the brown parcel tape would have been better) and carefully aligned with what should of been the ‘finished’ deck line. Once I was happy with that, a polyester filler was layed into the resulting triangular shape to bring the line up. After setting, clamps were moved to allow access to areas previously covered by clamps and further filler added. Once set, guide plank was removed and filler carefully sanded with 240 grit paper on a long board to fair in.

The process was relatively quick & easy to carry out however, it would have been easier still to get it right first time!! I’m reminded of Anders-DK’s words at the end of his posts -

                            'Real laziness is doing it right first time!'

We live and learn…