Member postings for Tim Rowe

Hi Chris

Have you got the servo screwed down really tight? They only need to be lightly nipped onto the grommets.

Try slackening the screws just a fraction so that the servo can comply.

Tim R

Hello Derek

When you make your new pattern it is important that you seal and wax it well. The sealing is to stop water from the plaster of Paris making the wood swell. This could split your mould or make the pattern difficult to get out, The wax will help the pattern to release.

Don't forget to taper the side of the pattern otherwise it will get locked into the mould. You would have to dig it out! The lead would also be locked into the mould which would have to be broken to get it out. That wouldn't matter so much if you only want to make one.

I would probably pre-mix the shot and resin to make sure every thing stuck together. If you pour it in afterwards it might not get everywhere and the shot would fall out.

Good luck

Tim R

Hello Billy

I can't see the photos. You need to check on the instructions on how to create an album and then how to transfer the photos into your posts.

How long is the boat and what does it weigh at the moment. Dimensions of your keel would also help.

Tim R

A cracker Ray

What edition of the Yachting World Annual?

Tim R

Hi Ray

Maybe some aluminium trim tabs at the stern that you could bend to adjust. They will only affect the trim when the boat is moving. Permanent ballast up front might may it quite bow-down at rest and slow speed.

Like the subject very much.

Tim R

Hi Ashley

I don't think Neil has that much choice as he is using polyester cured with a catalyst. You can buy resin without any accelerator and add your own to get a slightly longer cure time but the risk is a very long or inadequate cure. Most polyester or vinylester resins are pre-accelerated. You cannot reduce the catalyst or you will very definitely get an uncured moulding.

Hi Neil

Do you have any rovings? If so you can lay them along the internal corners of your plug. This will help avoid air entrapment if you have trouble getting the chop strand mat (CSM) into the corners. It also avoids having resin rich external corners in your mould which are liable to chip. If you don't have any you can tease the fibres out of the mat which will be around 40mm long and lay them into the corners the same way only it is a bit more fiddly.
You can also use rovings or chopped fibres to lay each side of the sharp edge of your propeller tunnels. This will effectively round off the corners and again help the first layers of CSM to lay over the corner without any voids. Most of the GRP work I do at the moment is motor cowls for model aircraft. It is very rewarding when it all turns out right.

Tim R

Hello Neil

I have been following you all along. It is exciting to watch and your posts are always informative.

I am intrigued to see how this will release. If you are planning to release diagonally are you expecting the card rail closest to the coming out with the mould and you will then have enough "spring" in the actual moulding to get it out? Secondly do you have a release draft angle between the top of the belting and the outside edge of the shaft tunnel?

I ask because I was a patternmaker for a GRP moulding company and I would get a right royal ribbing from the laminators if I had a hang-up and an even bigger one from the management. That would have happened if a kind hearted colleague hadn't pointed out my undercut!

Might you have to consider a supplementary joint line around your shaft tunnels? It would be a shame to damage your plug getting it out of the mould half.

Tim R

Well done Carl

Great job and some good looking aircraft in the background. On the water soon hopefully.

Tim R

Hi Ray

International Yacht Enamel is nice to use and has a lovely smell. You may find you need to use their undercoats as well to get good coverage.

I am using Interprotect, which is two-pack epoxy primer on the Thames Barge Kimberley. It was a bit expensive but goes a long way. It is amazing how it hardens up balsa and is very easy to sand. The shelf life is good so it will last for many models and hopefully end up being good value.

I have been mainly lurking for quite a while but watching with interest the various projects underway.

Tim R

Hi Ray

I have already bought shares in SLEC.

Tell me what paints you are using and I will buy shares with them too!

Tim R

Hello Paul

That would be fire and explosion proof from the outside.

One lights up and the rest go too.

Don't stand in the way of the door!!!

Tim R

Hello Richard

Just a detail if you don't mind me pointing it out. You have added the engine bearers but in real life they would never rest directly on the planking. In the case of your clinker hull they would rest on the timbers / ribs whatever you like to call them and may or may not touch the planking. In your case, the weight of the engine is trying to push the planking off the timbers and it time it would.

A completely true to scale hull would have timbers spaced much closer together. At the moment you are resting on two. The longitudinal bearers on a full scale boat would probably rest on at least four and also extend at least one spacing past the front and rear of the engine to further spread the load.

Great hull and great project though. Watching with interest along with all these other builds.

Tim R

I served my apprenticeship with Appledore Shipyard in North Devon. It was twinned with Sunderland Shipbuilder and both were owned by Court Line who had travel and airline interests. Both yards were unique in the UK at the time because the ships were 95% completed under cover in a dry dock. Another first were the buildings that were built by Condor of Winchester and were the largest single span covered buildings in the UK.

At Appledore the high tidal range o the Bristol Channel allowed the ships to by floated out. The capacity at Appledore was up to 10,000 GT and slightly larger at Sunderland. Construction was completely modular.

There were up to 6 ships under construction at any one time in various stages:
Planning
Stocking
Cutting
Fabrication
Assembly
Fit-Out

The whole operation was geared to the Lunar cycle (tides) and on average we launched a ship every 8 weeks.

No operation in the UK could get anywhere close to that.

I came out as a fully qualified shipwright 1973 50 1977

Tim R

Note to myself

"Must but shares in Planet"

Tim R

Hello Ray

I let my subscription lapse after the articles had gone their cycle as they eventually do. I have more free plans than I know what to do with and the Minimoa would be too big for me. I get lots of enjoyment watching other people build such beauties.

Bated breath Ashley!

Tim R

Hello Ray

I knew it would come good for a plan. I have a subscription now so I will get it.

Nice one.

Tim R

I have wondered why that is Chris? Is it to keep the end of the stern tube above the normal waterline and therefore remove the risk of leaks.

Ray won't mind I am sure. I have moved the motor as far aft as I possibly can which is actually quite a lot. I made a cardboard cut-out of the motor profile to see where it will go. Another advantage to me is that I can now dispense with the forward hatch. I am happy to trade this off for a minor leak.

It would be good to know.

Tim R

It is very hard to imagine a designer of a full size boat being happy with producing a bow down attitude at rest. I am not talking about about extreme or racing boats but boats that people buy to go cruising in. The normal datum for a boat is either the waterline or an arbitrary line parallel to the waterline but below the deepest part of the keel (the latter most common for motor boats). All the bulkheads, interior joinery and the cabin soles will relate to the datum either being at right angles (bulkheads) or parallel (cabin sole). If the weight distribution is wrong and the boat is bow down against it's designed waterline at rest it would be very noticeable inside and unnatural. It is very odd and slightly uncomfortable and would not be tolerated.

Fore and aft trim at rest is therefore important. Likewise it is not good to have a permanent list. Trim errors at the sort of angles we are talking about have very little effect stability. A boat can be significantly out of trim and still be perfectly stable. The extremes however can be quite dangerous and a classic example will probably be familiar to those who sail dinghies or use speedboats. If you climb onto the foredeck and the stern comes out of the water the boat becomes unstable. If you mate then joins you, you are very likely to capsize. This is because you have made the waterplane very narrow at the bow and useful waterplane is now in fresh air.

Richard is right when the subject moves to dynamic stability and that is very often optimised for a certain speed range. A planing hull can be quite tender at rest and considerably more stable when on the plane. Push it too hard though and there is not enough boat in the water to provide the stability and it may get very twitchy, either chine walking or porpoising or BOTH. Round hull semi-displacement boats that may be perfectly happy up to say 20 knots and can, and have been known become dynamically unstable if pushed to far. Very scary!

In my experience trim is a good word to describe how a vessel sits at rest and attitude best describes the position the boat adopts when the boat is moving. I think it is quite useful to make the distinction.

As far as adding weights is concerned if there if there is nothing left to move, it is almost always better to move a lighter weight as far away as possible from the longitudinal centre of buoyancy. The shorter the distance the more weight you have to add to shift the longitudinal centre of gravity.

I have the Precedent kit to be fitted with an Enya 35 marine glow engine. The instructions warn about the tendency for the complete boat to be bow down at rest (out of trim). For this reason I have worked to get the engine about 40mm back from where it was shown on the plan and everything else will have the possibility of going aft as far as possible. Let's see if that works.

Tim R

I get mine from SailsEtc.

Looking at your photos, there is reinforcement around the eyelets. Same sort of thing like I said is required at both ends of the join.

Tim R

Ashely has it about right. I make sails, so clean off the old residue and use new double-sided tape. If it is Mylar you can use acetone to get rid of the old stuff. If not, use white spirit.

You could make the overlap of the joints a fraction wider. You will lose a small amount of luff length if you do. The most important thing is to reinforce the join at each end to stop the "peeling" effect. The best material to use is Mylar tape on films. On woven materials I use deck patch or sail number material. Cut out a disc or a diamond shape and fold it over the end of the join.

Tim R