Saturday, 9 June 2012

Marauder, a good wooden boat

This boat has been around since I arrived in Cape Town back in 1968, she was one of the best boats on the water then and as this picture I took last monday shows, there is nothing much thats changed.

You may well question why I have posted the picture of a power boat that is not one of our CNC cut wooden boat kits?  The reason is quite simple, Marauder is a wooden boat, now at least 45 years old and still in good service. Designed by Renato Levi, she was a classic when launched and will remain so for a very long time.

The hull will be in a cold molded timber, probably laminated with resorcinol glues, she would last longer today using our laminating and constuction epoxy.

pictures by R McBride

My first life raft came off this boat when DOT decided the three RFD ones on the boat were not suitable for a commercial fishing boat. I bought one of the two six man rafts for R1500.


Stolen Time book now on Amazon Books

The book has been years in the making, as much a part of having to get it into a Kindle type format as
the actual writing of the story, it should be released today.

This is the Amazon link, downloded as of 12th June 2012 and active today, give it a try, you can read the first eight pages for free!

I will post the link to the book when its open.

This is one of those sailing adventure books, starts here in Cape Town and goes across the South Atlantic Ocean to the Amazon jungle, the yacht is a super large and super fast catmaran, science fiction has never been better but there is a lot of truth writen into the story.


Friday, 8 June 2012

Goodman Mezzo 2 speaker capacitors

I did some stuff on this a while back but never quite got a reply to the question, as to why a noise was on one speaker and what did the circuit board in the enclosure do?

This is part of the frequency control board, I have now found on a forum that the capacitor (in blue) can age and would affect the audio. I have checked out its markings, Hunts, Reversible. 8uf 150v dc JB2973 T AYI

I now need to source two new ones, one for each speaker to balance things out.
News in today on what some parts may do,

I don't know what that circuit does in the speakers - I suspect
its job is to split the high-frequencies for the tweeter vs the low freq for
the bass/woofer thing. The circular coils are "toroids" - they act as
frequency filters and chokes.

Info on the same subject as supplied by ham man Justin, so I know a lot more on the subject than when I started this morning.

Inside the Goodmans Mezzo 2 speaker, I can change the capacitors myself.

News from my technical bod friend in England, I had sent him a link to a forum discussing similar speakers with two different capacitors in.

Hi Roy,

I read through that guys question and I think the short answer he received is sound advice. If you have different caps on similar speakers that is odd but it all depends on what the caps are doing. As sound is dependant on frequency to activate the speaker coils and therefore the diaphragm to move the air?

You don't want too much smoothing or you end up with almost DC so its very important to stick to the makers range. If there is high pitched noise coming through I would think it means that the high frequency smoothing is not doing its job and it could be as a result of a deteriorating capacitor. As they are quite cheap things, if its easy to replace them it may be worth while as they don't last forever and are very simple things inside just layers of what looks like tin foil and some sort of insulation which can break down over time. mf is microfarad while the other one for which I have no key on the computer is peaka-farad or something like that and is very much smaller.

I assume these different caps are in different parts of the circuit? I would think the larger ones the mf are to deal with base frequencies while the peaka's are to do with high frequency but I'm no expert on sound systems. If you do change them use identical caps in both speakers, however they may have used different ones due to some variation in the speaker coils, it only takes a couple of extra windings on one speaker for it to require different treatment.


Sounds like good advice as Notty says.


March 28th 2013.

I have managed to find some caps to the same specification, they are in the post so I will soon be able to change the existing ones for the new ones. The old ones will be about 47 years old, time was not on their side?

More on the subject when the new ones are fitted.

Time to drop that anchor

There are many types of anchor, the Hout Bay Yacht Club has a nice twin fluke design, I guess its dated about 1750 to 1850, either way they have just dropped it.

Where did we find this, easy enough to see why it was lost, the eye in the shank has gone missing.

Check the size of this brute, its solid cast iron, none of that flimsy welded stuff for the HBYC.

Last I saw was the HBYC Vice Commodore, Jeremy Nel, discussing its placement with a club employee.

Before those nice flukes were buried, I really do hope they display the full anchor next time!


Thursday, 7 June 2012

How to service the Yamaha P-320 turntable

With vinyl records making a bit of a come back, my own audio system has been seeing regular use.. The system is nothing startling and in fact its got a low output Sony amplifier that just puts out 20 watts per channel.

The speakers to me are special being Goodmans Mezzo 2, said to be the best of the best when they came onto the audio scene around thirty years back?
The turntable is a Yamaha P-320 and looking at its inside, plus the cast alloy turntable disc, its clear to see Yamaha  made that well too.

The Yamaha P-320 turntable, bought new in July 1990 from Hamrad with the Sony multi function amplifier, its now 22 years old.

This was writen about by me before, about two years back.

The turntable rubber mat when removed reveals the very nice alloy disc, to the left is the access to the rubber band drive belt, which fits around the the underside of the disc and around the drive motor rotor.

Recently I have noticed a noise in the left hand speaker, I checked inside both speakers and discovered nothing, switching left to right did not help, neither did new quality twin flex cables, I then supspected a fault in the Sony amplifier?

Disconnect the power supply and remove the complete stylus mount when your working on the table.

 I then thought to check the turntable out, making it 100% level certainally helped, I increased the anti skate bias as well, the sound was by now much smoother and clearer, I used a Matt Bianco album to get a good selection of musical instrument sounds.

When the alloy table was removed, I found a probable cause of noise right away, the rubber belt drive pin was quite loose, plus it had a central and uneven build up of rubber that had come off the two belts used in its lifetime, this I managed to remove with my finger nail. On closer inspection I found the rubber bushes around the mount screws had shrunk.

I then removed each screw one at a time and replaced them using a thin rubber washer, the drive pin was now secure. Note the by now clean drive pin surface. New drive belts are available
locally in Cape Town.

With the bottom cover screws removed, this includes the four spring mounted rubber feet, I could access the works and see if any obvious faults existed?
The drive motor is the small round item on the right with yellow,white,black and red wires coming from it.

Remove all 10 screws, lift the metal cover from the side closest to you in the picture, hinge it back and then find the small earth cable in the back left hand corner, do not break the cable or its soldered joints.

The Yamaha drive motor, I brushed the inside of the player to move dust, then vacumed it clean.

To refit the alloy table, mount the drive belt on it, then fit the table on the center pin, you can then access the belt and move it over to the drive pin, a toothpick will suit this job.

The model number.

Ready to play again, make sure you refit the rubber mat the right way up.

Check the three crossed tuning forks, proof that its a real Yamaha!

Yamaha P-320 turntable info.

A test play had me listening to some clean and pure audio sound, the fix worked but I still get feedback from the left speaker when the stylus is down and I tap the plastic dust cover lightly, why?

I now suspect the stylus fitting, as fitting another stylus reduced the side noise.


Technical stuff.


Drive system: belt drive
Motor: v servo dc motor
Platter: 300mm, 0.9kg, diecast aluminium
Speeds: 33 and 45rpm
Signal to noise ratio: better than 70dB
Wow and flutter: less than 0.04% WRMS
Tonearm: swinging straight arm
Effective length: 222mm
Overhang: 16mm
Tracking force: static balanced 0-3g
Effective mass: 11g
Offset angle: 23 degrees
Dimensions: 435 x 111 x 378mm
Weight: 5.8kg


Wednesday, 6 June 2012

How to repair a British Seagull outboard that runs slowly

Recently we did a back outboard test to see what performance we can get from old and new outboards, I say old and new but the old engine was 51 years old and the newest about 6 years old, its relative? The larger Yamaha 5hp motor gave us 10.1 knots and the Mercury 2.5hp motor gave 5.6 knots, so the smaller engine was doing rather well.

The test was less successful  than we expected, being let down by both Seagull motors, both had the same sort of  misfire and would not reach anywhere near full revs, they needed a lot of choke and a wide throttle.
I contacted John at SOS (save our seagulls) in Essex, England, he suggested there was dirt in the carburetor jet? Cleaning one carb sorted that motor out and it was soon running cleanly and the choke could be opened on firing right away.

The other motor refused to run properly, even after stripping the carb down twice, the only indication I could get was when the fuel bowl was manually over filled, the problem went away untill the fuel level went down, now what?  What was this problem all about, well I had already raised the level of the float in the petrol bowl, what else can I now do?

The air compensator is the round cover on the carburetor. The motor is a 4.5hp unit and is around 35 years old?

Checking the workshop manual I saw that on the Villiers carburetor page there was one difference between  the two carbs on the Seagull motors, the one that ran well had an Air Compensator while the one that still would not run well did not, I wonder ?  thought I.

Note that air correction hole, I think without the compensator being fitted, too much air is fed into the hole, the pressure then upsets the fuel level?

The new plastic air compensator had arrived the same day I discovered its need. Not cheap at about 8 Pounds Sterling, plus pack and post, a Pound to write the invoice into Pay-Pal and when it landed, the packeage was opened by the customs and a 20% duty plus 14% vat was added. I think this bit of plastic cost me R230 and more!

I removed the air compensator from the one motor and fitted it to the motor that would not run properly, it started right away and ran cleanly! So we can now complete the back to back test, this time a blog viewer has also offered me his electric outboard, we can try that off his battery and also a solar panel designed to suit the electric outboard.

How good is this.


Refitting a Hillman Imps 998cc steel liners

The Imps steel liners should be bonded into the alloy block using Loctite 648 retaining fluid, not cheap but its the right product for the job. If for any reason you need to remove those liners, a mandrel will require making as a press tool, another size of liner can be turned down to fit inside the Imps liner. You will require the use of a standard garage hydraulic press to do the liner removal, I was told its an easy job this way.

Loctite 648 retaining fluid.

The alloy Imp block as it looks after the original liners are machined away, this block was later welded and the alloy liners support holes were distorted about 0.003" meaning the steel liners would no longer fit.

In the case of the 998cc block made here, the liners were not exactly level and I asked they be pressed out and I would refit them myself.

The question now was how do I get those new steel liners to fit back in the holes they came out of? They were numbered using a black felt tipped pen.

The perfect tool was a low priced solution to the question, the flapper sander is 80mm in diameter, the alloy hole is 77mm (about) and with a bit of hand reforming, I made the flapper sander fit. Using a Bosch 500 watt electric drill and a low speed, I was able to lightly sand the deformed alloy untill the steel liners fitted.

Low speed is very important, move the drill up and down as you sand, never stay in one position while the drill is working.

We need a drop in fit, this is because we need to coat the liners with the Loctite 648, then refit by hand before lightly bolting down a re faced cylinder head to give us a perfectly flat set of four 998cc Imp steel liners.

Looking inside when the liners are in place, I have used a good Mk1 cylinder head to hold the loose liners down.

The liners are back in the block, prooving we can do this kind of machine work ourselves. The welding on the top of the block was milled off first.

The first fit was done on a warm afternoon, the next day they would not come out, such was the fit and with a by now cold block, they had become fast. I warmed the alloy block up in the morning sun (its winter) then I was able to remove the liners again. I lightly dressed the alloy sockets down with the flapper sander and was then able to fit and remove the liners.

Block saved? well we still need to check the crank journals are true but we are becoming close to having a good 998cc Imp block.

I have just checked the 998cc Imp block more fully, sort of one thing at a time, its as I suspected , the block is bent. Down about 0.015' in the center and more to the rear of the central journal. This in effect means the next step is to skim top and bottom surfaces and then line bore the journal, not a job Roy can do. It may just be possible that the line bore can just be on the center journal, if so its easy, they remove metal from the cap face, the cap then is higher into the block and means they can rebore, simple but what will it cost?


Tuesday, 5 June 2012

The Queens Jubilee day for us

Seen here on a winters day and having a beer is Athol, skipper and owner of yacht Perazim, he joined us for a sail past the East Fort in Hout Bay to pay our respects to the Queen.

John off  Rosie Dry supplied the beer.

The HBYC posted some pictures as well

Another John, this time off yacht Polaris joined us too.

John was hanging on to Druma our dog for a while, we then put the life vest on Druma, we all relaxed a lot more then!

We had been informed that the East Fort's old cannons would be fired at 3pm, it never happened, we were back in the harbour by the time they fired them.

We at least flew some flags, at the back of the boat was the OCC Port Officers flag, from the starboard side we flew the South African, then Union flags, followed by the OCC, HBYC and TBA burgees.

How nice was this.


How to mill the top edge of a Hillman Imp Timing cover

The timing cover should be milled at the same time as the block should it be re surfaced? In this case it was forgotton and stood proud by about 0.008" or so?
When this is the case, the cylinder head gasket will not tighten level and the excess alloy must be removed.

The jig or template I made for the removal of alloy on the block edges has been re cut to expose the area over the timing chain cover. Even with bolts some distance away, the 32mm thick MDF (supawood) stays perfectly flat, note the plastic safety glasses, a must have when milling metal is concerned. Thinner MDF should also work, say down to 18mm thick but thicker is better.

Having done much smaller areas the day before, I knew this was going to work, the process was now understood and went very quickly. Do not over tighten the bolts, you may introduce distortion?

The Makita 3612 router, this model has an auto brake and stops very quickly, recomended!

The 13mm milling cutter, a tungsten tipped type will also work but the finish will not be as smooth?

The template will be stored away for other work on alloy Hillman Imp blocks.

The finished job, I took around three cuts to make the load on the milling cutter less, this way you can slowly move down to the required depth.

Click on the pictures, they should enlarge.

The milled Hillman Imp alloy block and timing cover. This fix cost me nothing, all the tools were to hand, scrap MDF was the template material and I did not have the expense of a machine shop or the traveling time there and back.

Next I will show you how I fitted the 998cc steel liners into the alloy sockets which had distorted some 0.003" ?

Works for me!


A Didi Retro 29 boat test (before we even build one)

Justin Phillips has really got his mind into the new design by Dudley Dix, so much so he seems to have been on the boat and sailing it in our local regattas!

Check the link:

Justin has been reviewing yachts by many designers that are South African specific, they were all built here, many were also designed by South Africans as well.

We will soon be cutting the kit for boat 001, it will be built locally and in
Hout Bay, South Africa.