Ok, so I’m hoping to get some workshop time this weekend (it’s been ages since I made any progress) and I’m hoping to make a start on the deck beams and bulkheads / frames. From the first pdf file on your 1st post (http://www.rcsailing.net/forum1/showthread.php?5781-1-28-scale-ENTERPRISE-1930) I can see from the profile that there is a small amount of curvature to the deck beams (crown heights etc). Before I started the build I printed out all the relevent files full size and then aligned & taped the various pieces of A4 paper together. Unfortunately the sheerline& deckline came out rather pixellated / fuzzy and no amount of playing around has resulted in sharper images. I was hoping that you might be able to give me the amount of maximum deck crown height at station 6 from your original drawings, so that I can put the number into the following formula to create the remaing deck beams to the correct curvature.
So, last weekend resulted in zero workshop time. Best laid plans and all that…
I’ve had a little more success this weekend. ‘Enterprise’ now has a cradle of sorts, I’ve cut & nearly finished sanding the half and full bulkheads for stiffening the hull around the mastfoot/shroud base and ballast area. I’ve also managed to make a bit of progress on the deck beams - problem from last post resolved by enlarging one of Claudio’s pdf files to 470% (makes drawing full size) and measured off the computer screen. The maximum deck crown was 1/4" which correlates (in terms of orders of magnitude) with a traditional naval architects’ rule of thumb being that crown height should be between 1 1/2" & 3 1/4" for each 3’ run of beam. As Enterprise has a max beam at deck level of approx 21’4" (9 5/32" @ 1/28), this suggests a minimum deck crown of approx 10 5/8" (approx 3/8" @ 1/28) .
While the measured figure of 1/4" needs increasing by 50 % to achieve the suggested 3/8", I’m guessing that old ‘rules of thumb’ were applied generally to cruising yachts, motor yachts & commercial shipping. Foremost in their minds at the time wasn’t that particular rule of thumb; perhaps more leaning towards tearing up the old ‘rules’ and starting again for the very first J Class yacht.
Interestingly, while looking up various numbers and/or dimensions it became apparent that while Enterprise wasn’t quite the shortest J, that was Shamrock at 119’ 1", she was by some margin the beamiest at 23’.
I’ll try and get some pics posted here to show progress over the next few days.
I really can’t believe that it’s now been over a year since any progress was made although I guess I’ve had good reason…
I’m not going to start off by saying something ridiculous like ’ …so this weekend I’ll be getting on with blah blah blah…’ only to report on monday that the sum total of all effort amounted to a big fat zero!!
So, for the time being I intend to add additional pieces of glass cloth / tape by way of reinforcing highly streessed parts of the hull for example, the inside of the base of the keel where the ballast will be supported, additional cloth by way of rudder stock support and then of course the usual additional bulk where shrouds will need terminating at deck level. I’ll also be having a play around with rudder constructon - I did manage to produce a MK1 varient which proved to be far to heavy, being made from 3 shhets of 5.5mm ply laminated together with the appropriate hardware also bonded into place. I’ll see if I can dig out the rudder pictures and get them posted
My one question at this juncture regards the final shaping and fitting of bulkheads. I intend to use them to enable better mast foot loading distribution, a couple more to go between ballast sections which will hopefully further enable loads to be distributed and then finally a fwd & aft water tight bulhead. Point I was wanting to make was is it worth having a deckbeam as an integral part of the bulkhead or does this somehow overly complicate a fairly simple structure?
That’ll do for a much belated re-introduction & look forward to reading any comments that may be forth comming…
Hi Row,
I’m extremely happy to see that you are back onto the Enterprise and thinking about local reinforcements and what else.
“Good Work” then, this is the typical wish used in my county side substituting most of the time the classical 'Good Day"…
Cheers
ClaudioD
As mentioned previously, I’ve already cut and shaped pieces of ply to form the various structural bulkheads and it occured to me that when it comes to fitting them it would be rather useful if the hull was sitting level both fore & aft and side to side - fairly obvious really. Anyway, a year or so back I built a basic cradle to support the hull and with careful use of 40 & 60 grit papers Enterprise now sits level to her waterline.
So, the bulkheads. It’s still far to cold for epoxy at the moment (although this may be resolved if I can find a quiet corner inside somewhere…?!) so in the meantime I’ve been concentrating on the final shaping and trying to decide which ones to include. The definites so far are 3 & 4 as the mast foot & shroud base will be in this area. Other than that, I’ll probably go for a half height bulkhead at 5 and a further full one at 6. Reasons for 5 & 6 are that the hull shell is incredibly light & flexible by way of the internal ballast and the incorporation will spread the loading over a greater part of the hull & inwhales.
To date I’ve managed to cut & shape the inwhales (the amount of twist towards the stern prevented them from lying evenly so they’ve had an angle chamferred onto the lower inside face to compensate). Main bulkheads are ready for bonding (3, 4 & 6) and hopefully tomorrow will see ‘0’ ready (it takes the inner forestay load). Then I need to establish how to stiffen up the back end to take the backstay loadings.
One question that has me puzzled at the moment - having perused various build logs the inwhales generally appear to be installed flush with the hull shearline. Is there any particular reason for this as I was thinking of lowering the inwhales by the thickness of the ply sub deck (eventually I’d like to do a teak type deck) so that the ply end grain was afforded some protection.
That’s it for now,
Row
Edit: Forgot to mention - I’ve also carried out a floatation test with the bulkheads dry fitted and the ballast cut into sections & dropped into place. I’m pleased to report that ‘Enterprise’ floated slightly bows up (which I’m hoping the weight of the rig will resolve - required approximately 220g at mastfoot to bring level to w/l), so at this stage I owe a huge debt of gratitude to Claudio for his excellent design skills.
I’m typing this from my phone but once I get to the computer in a few days I’ll try and upload some pictures
Well, I’m not even going to look at the date of my last post, I’ve just been far to busy - where does the time go?!!
Anyway, onto the interesting stuff. Over the last week or so progress has been forthcoming at last, to that end, ‘Enterprise’ now has a pair of inwhales epoxied into place. They were awkward ‘b>g+£r$’ to fit owing to the twist in the sheerline as it approaches the stern. I initially opted for brute force and many clamps but to no avail - they just kept sliding slightly out of place which obviously wouldn’t work when it came to the gluing bit.
It then occurred to me that I’d had a similar problem with some of the hull planking (excessive twist) & I recalled that I’d used boiling water to soften them prior to fitting. So, I dug out an old electric kettle, filled it to quite a bit above maximum (this was necessary owing to the length that required twisting) and then lowered the plank into the water, switching the kettle on & off to maintain temps. This was done for approx 4 mins per plank (section was 5mm x 8mm). It was then gently clamped at the ‘soft’ end and again approximately 230mm from the end with the first clamp then left to hold the plank end with about 100 degrees of twist. Left it over night, following morning, success! Each plank had a permanent twist which aligned perfectly with the hull. Once I was perfectly satisfied of the fit & plank dryness a batch of epoxy was mixed with colloidal silica (stiffens the mix) and cellulose fibres (for strength) which was then loaded into a syringe to allow careful control of application. The inside of the hull had been abraded with 80 grit paper, the bonded surface of the wood left with a rough sawn finish and finally the whole lot was brought together with what seemed like hundreds of clamps. So thst the clamp pressure wouldn’t distort the sheerline in any way the outside of the hull had a left over plank bent around the sheerline to help spread the load.
Anyway, if I’ve managed to remember how to attach photo’s the following should give some idea of where I’m at. More very soon!!
Regards,
Row
By way of explanation, 1st two pics show inwhales installed, the second giving a better idea of their final fitted shape. 3rd pic shows frame 6 with limber hole cut to allow any water to drain through the hull (it shouldn’t really be necessary, I fully intend to have nothing but spiders’ webs in the bilges!!). 4th pic showing frames & deck beams dry fitted - They’ll be a few more deckbeams required for the hatches etc and then of course the kingplank can be let in to all the beams & frames. That’s the plan at the moment anyway …
Hi Row,
great job !! Hope to see the rest, like the Deck …
Don’t worry about time, we all have the same calendar !! heheh !!
With that, you are now much ahead on mine.
Considering possible removal, all my projects will go on stand by for a while …!!!
Cheers
ClaudioD
Hello Row, I just finished reading through your thread, certainly is a great deal of work.
I have a couple of questions which might seem ignorant regarding the reason for all of the work to make the hull out of wood then to all the work to make the single fibreglass hull?
The wood hull looked like it could have been used as the hull, yes, no?
The next question is regarding the lead, Is is not possible to use lead shot and cast it cold?
I ask these questions because I have little experience with such matters.
In short, the answer to both your questions comes down to weight.
In terms of the hull, its bare weight when made ‘properly’ from bits of tree comes in at 2068 grams, whereas the GRP hull with the inwhales bonded and the current frames & beams added to the scales gives a reading of 835 grams. If one were to compare both these numbers to the overall displacement of 6167g it very quickly becomes apparent that the GRP hull allows a far greater margin for the construction and more importantly permits the ballast to make up a far higher proportion of the overall weight / displacement. My basic understanding would suggest that the larger the model we build (in terms of displacement) then the less critical the ballast / displacement ratio becomes. As a practical example, a friend of mine has a yacht that displaces nearly 17 tons - however, the ballast is about 5.75 tons giving a ratio of about 34%, whereas this scale model of ‘Enterprise’ when finished should have a ratio of approx 63% - both hulls share a similar form: they’re both long keeled & both have relatively short waterlines compared to overall length. The main factor for the high ballast ratios is the wind. While we can produce scaled down models of virtually anything we choose what we can’t do is scale down our environment: 15 Knots of wind on a full size boat is still 15 Knots when we sail our 1/28, 1/20 or 1/8 scale boat.
Other ‘weapons’ we keep up our sleeves to compensate for the wind being so unhelpful is to use much longer fin & bulb combinations to increase the ‘righting moment’ of our yachts. We can also either reef or change the sail plan (different combinations of sails) or as the model yacht racers do, simply install a smaller rig.
Briefly, the ballasting question also ties in with the wind. The ‘righting moment’ is important for any sailing vessel and with models all we have is (usually) a lump of lead as low down as possible. With boats like Marbleheads, IOMs, AC120’s etc, they use a relatively small ‘lump’ attached to the end of a relatively long fin. With a true scale model we don’t have that luxury so we need to get as much of our ballast as possible as low down as possible. I don’t have the exact numbers to hand, but for a given volume packed with lead shot we get an equivalent density of 60 - 70% when compared to a solid casting. So yes, I could have used shot (there’s plenty of space in the keel area) but it wouldn’t have been the most efficient use of the weight. Their are plenty of people building scale yachts who also add a fin & bulb to improve righting and it may be that I too will have to go down that route but for the time being I want to keep the lines as near to original as possible. Time will tell …
Row ,
Thank you for your detailed and considered answer to my questions. I now understand the reasons, not having spent any time racing model boats this was an area that I did not understand. There is so much to learn.
Have you ever had one of those moments when you wake in the middle of the night knowing that you’ve made a monumental ‘mistake’?
I have…
Having spent a couple of hours yesterday afternoon epoxying some additional glass into the hull where the frames are to be bonded in, I woke in the early hours of this morning knowing that when I carefully weighed out the resin and then calculated 30% of the weight for the hardener (you know, 10% then multiply by 3), I kind of forgot all about the 3 bit… Needless to say, having had to go out this morning I’ve returned home to find a very sticky surface. You know, I even went to the trouble of applying peel ply… Oh well, out with the acetone and/or vinegar etc. So much for the frames going in this afternoon.
Thats why I love the West system with Pumps… I too have made the mixture mistake. spent a few bucks on the west pumps never a screw up with mixing since…
Sorry to hear about it… you’ll get it squared away…
Some of these pics were taken quite a while ago so you’ll have to excuse any vagueness in the descriptions.
1st off, marking the waterline. I experimented with pens/pencils clamped into stands with the hull set up with the waterline parallel to the bench which worked fine from station ‘0’ through to ‘8’ but as the hull runs aft towards station ‘10’ it became so flat that accuracy was nigh on impossible. I then decided to play around with a laser level with the hull set up level on one side of the workshop with the laser on the other (about 10’ or 3m away) with its height set the same as the w/l height to avoid parallax errors). Worked an absolute treat with a sharp line projected onto the hull side, it then being a simple matter of marking the hull every 50mm or so on the line so that tape could then be applied. (1st pic)
Once the designed waterline was established I then wanted to check the gunwale level side to side when floating, so the hull was ballasted, aft edge of keel taped up (hadn’t decided how to finish it at this point) and the hull was floated in the bath with a short level being used across the gunwales to check for any unevenness. As various datums were established so the hull was carefully sanded down to achieve level gunwales while also maintaining the sheer curve. (Next 2 pics)
More recently I’ve started to bond in the frames & bulkheads. The main bulkheads/ring frames have been bonded in with epoxy fillets onto an additional layer of epoxied glass which I’m hoping will prevent any bulkhead print-through and associated stress fracturing. I’m almost certainly over-engineering this - as I’ve said before my experience is with ‘big’ boats, so when she’s finished and seriously over weight then at least I’ll know why! I’m planning on using the fwd bulkhead (at station ‘0’) to attach sheeting turning blocks but also to possible retain some form of closed cell foam for floatation between it and the bow. The next 2 frames (stations ‘3’ & ‘4’) will take the mast & rig loads (I’ll be utilising a deck stepped mast to make any necessary adjustment straightforward). Frames at 4 & 6 also help to distribute the ballast load - I felt that 4Kg of lead being supported by such a thin hull was possibly asking too much! (remaining pics, which also show some of the deck beams temporarily slotted into place)
7 months since any meaningful progress, where does the time go? In my defence, err, well, I really can’t think of an excuse that will stand up to scrutiny…
There has been a modicum of thinking time invested; positioning of rudder servo; positioning of sail winch servo’s; positioning of deck hatches; ‘design’ & a little construction of standing rigging components (more like ‘make it up as you go along’) and a few more little bits and pieces buried deep within the grey matter. To that end, most of the deck beams are now bonded into place, an additional mid-ship frame has been added to support the sail winch mountings and an extra half bulkhead has been fitted to support the rudder tube which has also been epoxied into position. I’ll hopefully get a chance to dig out a camera & get some pictures posted to give some proof of progress!!
Ok, so 10 days since the last post and lots of saw dust made - keep changing my mind about sail winch positions & mounting options. It was suggested in an earlier series of posts to try and create a removable board with all the radio gear attached. No longer think this is going to be possible owing to a distinct lack of internal volume coupled with the rather large Hitec (785) winches I’ve acquired - they really are huge compared to ‘standard’ size servos. However, I do think I’ve come up with a cunning plan to make them relatively easy to remove for servicing etc. Hopefully I’ll get a few pics up in the not too distant future…
Brief update: Just to reiterate from an earlier post, all the deck beams are bonded in place (still need to fit carlins for main, aft and fore hatch), an additional half bulkhead has been fitted to support the rudder tube & servo AND a mounting plate has been made & fitted for the sail winch servos (3 of them). In addition, the forward turning blocks have also been semi-fitted for the closed loop sheeting arrangement - these will be removable through the forward hatch for servicing etc.
Anyway, enough of the writing bit, onto the pictures!
Hi Row,
Hope your back is OK now.
Pleased to see progress, far ahead on me.
The removal has blocked everything and in June another definitive removal will take place in our fully restored flat. I still need to sort out the garage affair to see if a lab can be integrated.
The only activity is the one on computer, the last design is a revised Esterel Class M with round bottom.
Good luck for future ‘work’ !
Cheers
Claudio