Topic: A 50' Thames class lifeboat....A new lifeboat mould. (Read 20190 times)

Neil · « **Reply #25 on:** October 06, 2014, 10:33:56 am »

the moulding process has started, and the first quarter has been successfully fitted, held with plastecine, blutack and masking tape..........to make a none too sturdy fit, but it has worked.....filling between flange and hull with plastecice, and then laying some gelcoat onto it................

there is absolutely no strength in gelcoat what so ever and should I attempt to do the next quarter a gentle knock on this flange even would crack it................so as soon as the gelcoat has gone off I will lay a couple of thin layers of chop strand matting over the joint between flange and hull and allow to go off before fitting the next part of the flange.

Neil · « **Reply #26 on:** October 06, 2014, 12:24:03 pm »

well..........it's going better that expected.......the first quarter been laid up along with the flanges of the two cabins to give them some strength..........

the second quarter has had the flange added and will be gel coated after lunch.......

so hopefully by tomorrow evening the most difficult part of the job will be complete, and the cabin halves also moulded.............I mix enough resin/catylist to do the hull and cabin halves.....which will be done within the next couple of days.

the hull will follow.

Neil · « **Reply #27 on:** October 06, 2014, 01:16:13 pm »

second quarter gelcoat laid up and the small patches where the masking tape helt the flange and have now been removed, have also been gelled up to take the matting eventually.

Neil · « **Reply #28 on:** October 06, 2014, 04:11:28 pm »

Now that both sides of the fore deck flanges have been secured by laying down a couple of layers of matting the final part of this process was to remove the remaining pieces of masking tape holding the flanges to the hull.....these small areas have been gel coated ready for some matting, before I start on the aft end this evening.

all gaps between the flanges and the hull were pre filled with plastecine to give a good "no gap" fit of the moulding.

U-33 · « **Reply #29 on:** October 06, 2014, 04:35:19 pm »

Now stop mucking about making lifeboat hulls, Neil....I need a radio box building.

Rich

Neil · « **Reply #30 on:** October 06, 2014, 06:31:59 pm »

was once asked by a mate of mine who is a member of the Magic Circle inner wheel.to make him a replica of the camera boxes we see on the road sides.......he had a routine, during one of his comedy acts.......but in the end never got round to it.......that would have been fun, lol................as for radio boxes, mate.................wouldn't have a clue what you mean.

Neil · « **Reply #31 on:** October 06, 2014, 06:39:52 pm »

and back to the model................well, when I started this this morning, I never thought how easy it would actually flow, and have just laid up the third quarter of the boat.......and quite possibly the hardest of the four sections.........as it is one of the longer sections, has a step in it at the break of the deck and was trial by error.....the last one I'll have learned by my previous trials and mistakes..........and that one will do tomorrow, as my back is now killing me and am going for a hot bath............high as a kite on fumes and giddy with success.

U-33 · « **Reply #32 on:** October 06, 2014, 07:17:40 pm »

Back to radio boxes for a second...it's a long narrow box, with tapered sides and ends, and a top flange cut out to have a clear lid screwed down on it.

Rich

Neil · « **Reply #33 on:** October 07, 2014, 09:44:36 am »

this has got to have been the most unorthodox method of laying up the first part of a mould I have ever done, but after weeks of frustration with the flanges, it has finally worked and the last quarter of the surrounding flange has been added and gelcoated up to.............with the strengthening matting going on in around an hour's time..........then it will be a quick fill where I have missed any of the area and then down to lay up the section of the mould to thicken it up to working status.

gribeauval · « **Reply #34 on:** October 07, 2014, 11:55:21 am »

Well done Neil, I knew you would crack the problem!!

Lateral thinking is the only way to go.

Mike

P.S. I have started thinking about another one off the RNLI had in service, ON 725 from the 1930's.

Neil · « **Reply #35 on:** October 07, 2014, 12:45:47 pm »

would that be a nice little harbour class boat with hb as intitials

gribeauval · « **Reply #36 on:** October 07, 2014, 02:25:19 pm »

Nope! 64 ft Thornycroft, a one off built for Dover, served there 1930-40, requisitioned for Air Sea Rescue in 1940.

Can't find much info about her design or lines for the hull at the moment.

Neil · « **Reply #37 on:** October 07, 2014, 04:51:03 pm »

you could ask the editor of model boats mag where ( I think ) Brian King built a model of her........but someone did in the 1980's and it appeared in the mag...................so there must be lines around somewhere. neil

Neil · « **Reply #38 on:** October 07, 2014, 07:50:43 pm »

well, never have I farted around so much laying up one part of a mould in my life................but it has taught me something......that with (as Mike says) lateral thinking, a lot of patience and much perseverance, you can mould almost anything, even if it is in stages, bit by bit...........

and after 2 full days I have finally managed to mould the deck for the Thames class lifeboat in entirety...........just hope it will come out of the mould easier than it went into one.................tomorrow I will thicken the mould up with a few layers of matting so that it will be durable for a good few mouldings in the future. Once this has been done, the mould will be left in situ so that the hull itself can be moulded up to the deck ( splittable of course).

the surface has been sanded free of lumps and bumps so that the future layers will have a good flat key to adhere to.

Neil · « **Reply #39 on:** October 08, 2014, 04:42:19 pm »

first parts of moulds all trimmed, cleaned up, flanges taken off and waxed up and now waiting for the second part to be laid up..........that is, all except the bare side of the smaller rear cabin which seems to have taken badly to spillage of resin on the untouched side........will have to clean this before I proceed any further with it............but only a little time will put it right.

the trimming up of the grp was done with my trusty jig saw fitted with a diamond tipped blade................cost a fortune but worth it as gives a good clean cut and goes through 1/4 inch grp like a hot knife through butter.

Neil · « **Reply #40 on:** October 09, 2014, 09:06:56 pm »

the flange for the hull split mould has now been added in the same way it was for the deck and the starboard side of the hull has been laid up with gelcoat........the first side will be laid up with matting tomorrow morning.

Neil · « **Reply #41 on:** October 10, 2014, 02:24:53 pm »

as promised last night I laid up a bonding strip and 1 layer of grp onto the gelcoat...........some recommend doing this onto gelcoat within 12 hours, some say 24...........but I always try to get my first layer on at the latest within the 12 hours so that it will bond into the gel.........and succeeded in doing this before 09.00 this morning.........then took pooch for a walk so that it could cure, and then this afternoon I laid the full working 4 layers of matting up to give the mould some substance............and here are the results.

you'll notice that the flange has been pulled over to one side by the heat and contraction of the resin whilst curing..........it hasn't gone too far so the mould will be workable once the other side has been laid up to the sloping part..................haven't had this happen to such a degree before but I don't intend to do anything about it at this point ..............should it have been a major problem I might have got my hair dryer onto it and tried to pull it over whilst hot...............but hey ho!! it's not an insurmountable problem.

Neil · « **Reply #42 on:** October 10, 2014, 07:33:27 pm »

A bit of a cock up.............trimmed the grp off and removed the flange, to find that that the grp flange had taken a lean away from the keel of the boat so much that there was a gap of around 1/8th inch between the flange and the keel.....

not insurmountable n the grand scheme of things as I could fill the gap with some plastecine................but I decided to give it a go and try to bend the grp back into place by heating it up with my hot air gun firstly and clamping it in place to cool down.........hopefully it will reset itself once cooled down...........if not back to idea 1.

Neil · « **Reply #43 on:** October 11, 2014, 10:46:48 am »

last night I heated up the flange whilst it was still in the curing stage to eradicate a gap of about 3mm that had opened up between the keel and the flange when the flange moved during moulding, and cramped it up.

removed the cramps this morning to find success....the gap around 2 inches long had closed up to around 0.5 mm which I have now filled with plastecine, ready for moulding...........I'll later wax it all up and then start on the second side of the mould.

Neil · « **Reply #44 on:** October 12, 2014, 05:08:11 pm »

last part of the moulding now in progress...the remaining half of the hull and the two cabins have been laid up with the gelcoat.

a little tip here for anyone wanting to do some of their own fibre glassinf for the first time.....

the glass matting comes in different weights....they now sell in grams weight, but I have always worked in ounce weight, and bar stating the obvious, the lower the weight, the thinner the matting..............and for model boats the thinner the matt, the easier it is to mould, because the usual instruments for rolling the resin into the matting such as the parsley and ribbed rollers are very hard to use in a tight space of a small hull.............but the thinner the weight the more expensive per square metre it is...............so I normally buy a 1.5 or 2 ounce matting ( or gram equivalent.

I then cut it into manageable sizes for the mould I am laying up, and then I split the layers just as one would split slates for roof tiling............I then get twice the coverage for a minimal extra outlay of money for the same square meterage.

Neil · « **Reply #45 on:** October 13, 2014, 10:15:11 am »

the moulds are now all but finished................

the cabin moulds have both been laid up both halves and just need trimming and then drilling of the flanges with a 6mm bit to take the 6mm roofing bolts that hold them together.

the hull has been trimmed and drilled. the flange for the deck to hull has been drilled every 300 mm space approx., .............done this way because it will not be bolted to the hull except for storage purposes and therefore to keep it from twisting.

However the flange between the two halves of the hull has been drilled at 100mm spaces (approx.) so that it can be bolted together when laying up a hull moulding.

The drill holes on the deck and hull flanges on both mouldings will be masked off before waxing up to stop any ingress of resin or matting into the hole.

gribeauval · « **Reply #46 on:** October 13, 2014, 01:46:01 pm »

It's just like Christmas!! Can't wait for the "prezzies" to be unwraped.

Mike

Neil · « **Reply #47 on:** October 13, 2014, 03:27:58 pm »

it's that first crack of the mould parting with a moulding in it, Mike......the anticipation, the trepidation as to whether you've laid it up properly.........will it pop out without damage............all thoughts going through my head now...........and won't know till Wednesday................ooohhhhh, just got to grit my teeth and bare the anticipation

Neil · « **Reply #48 on:** October 13, 2014, 07:17:47 pm »

well, that was one hell of a struggle to split the mould of the hull.........especially with the deck also playing against the hull halves...........and finally on removing the deck mould, there was slight damage to the gelcoat on the fore hatch which will have to be filled and sanded down, with a small amount of gelcoat to fill the hole.

the paint work on the hull plug has been damaged, but little else in the process, but because of the hull shape, especially the tumbleholme on the fore bow area it has been a tricky mould to separate from the plug.

Mike Pendlebury, aka Gribeauval made the plug, and with my agreement used polyurethane varnish to finish the hull plug............I now wonder in hindsight, even though the usual release agents were used, may be the polyester resin in the grp might have acted as a bond to this rather than a barrier and that is why it took so much brute force to separate the mould from the plug.

gribeauval · « **Reply #49 on:** October 13, 2014, 08:07:31 pm »

I'm just releived that it came out of the mould at all!!

As you said in the beginning all the wax would need removing so removing damaged paint is no problem at all mate.

Mike

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Author Topic: A 50' Thames class lifeboat....A new lifeboat mould. (Read 20190 times)