All,

The trials and tribulations over the last few months are over, and the good ship Slingshot can now make pace under her own steam (well...diesel at least).

The MD5B has had a number of large spanners thrown at it, and the green legacy of engine building of a bygone (thank god) era is currently purring like a pussy cat (albiet with a bit of a hairball).

Though she smokes a bit on full chat...the question is....what is full chat.

I did a run in both directions against and with the tide and wind today, and splitting the SOG on the GPS gave me 3.8 knots flat out, with a clean bottom (cleaned yesterday).....seems to me a pretty woeful speed....would take me a day to get to most of our starting lines.

Is that reasonable.....I'm not saying the engine is in perfect tune, but what would those of you with an MD5 and S110 saildrive expect to get.

The thing is 7.5hp (in it's prime !!), but I bet you get more out of a 4hp outboard ??

Give me a rough idea and I'll see if I need to pull the spanners out again.

Cheers,

Keith in Singapore

Hi Keith,
good to hear that the engione is fixed.

I have a 4hp outboard so I'm not sure how useful this will be but I can get 4.5-5Kts in flat calm conditions and this drops off rapidly if there is a chop. I would suggest that with an inboard you should be able to achieve this and would have less of a problem than me with wash/waves slowing you down.

It could however be your prop that has the wrong pitch but I think it unlikley if it has been on for a while.

The thoretical max speed of a GK24 (without surfing) is going to be around 5.5kts if you get close to this you are doing quite well.

Scallywag who I was sailing with this weekend have a 13hp Beta engine and they can do about 5.5 ish, however Graphik have the same engine and struggles to do 5??

Hope this helps, G

Keith,

I had a 5B on a saildrive in Gate Krasher for years, and we could get 5 kts out of it, even when the valves were losing so much compression that it needed a good dose of Easystart to get it going (and it smoked like a chimney at full throttle too).

I can get an easy 5 out of my Beta 10 now, without needing anything like full throttle.

I'd probably put up with 3.8 kts, as long as it could still push you along at that speed in a reasonable breeze.

Steve.
Gate Krasher IV
GK211

With a Yanmar 1GM (7) and a 13x8 2 blade prop and NO **** JAPANESE SEAWEED on the prop and a clean hull , we manage 5 to 5.5 knots in flat water, with the cooling water just going grey.

This translates to 2 knots into the waves off Dartmouth and 6 knots going the other way down the waves ....

With seaweed this is 1.5 knots in flat water and lots of smoke and the head gasket goes after 5 hours.

3.8 knots is a bit low, the smoke indicates that you need more air to the engine, the prop is too large or coarsely pitched, or the injector needs a 'service' = clean the carbon off with a toothbrush...

But it is usable, and the prop will still grip the water in waves unlike outboards.

Thanks for the input.

It's running with a 14x6 standard Volvo folding prop (this prop is apparently unique for the reduction ratio with the MD5 / S110 combination), so am assuming it's a correct set up.

However, I'll check that when she's out of the water - She had a new prop a few years ago, and a few new blades since, and given the availability of spares in Singapore a 'standard' 14x8 could be fitted, which may explain why the revs are down.

She does rev higher in astern, but expected due to prop being less efficient.

There are a few more tweaks to be done. Have to admit the black smoke is not significant, and it's the cooling water getting sooty more than the exhaust gas itself. So it doesn't seem to be grossly overloaded (i.e. over course prop), more likely governed at the engine end. It's a great starter (now) with apparently good compression (head was off and valves 'inspected' 2 months ago).

She may just be running a bit rich - she'll be getting enough air as the engine compartment 'leaks' like a sieve - evident by the ear drum bleeding noise down below (another job !).

In the manual there is a note that says if it gives black smoke, turn a screw inside the control housing - however they don't say what this screw is / does (useful....!!) or which way to turn for less, or indeed more (could be useful to ward of pirates...!!), smoke.

The manual tells you how to pull it apart and put it all back together, but there's nothing on how to set anything up except the injector pump timing.

So it's a bit difficult to know how to 'gas the girl up'.

Therefore anybody with any advice on actually tuning an MD5 for optimum running would be appreciated.

Cheers,

Keith in Singapore

Well slowly but surely, after a good few hours thrashing (enough to burn 20 litres of diesel), the revs are slowly increasing, as is the hull speed.

Almost hitting a breakneck 5 knots now.

The black smoke has (almost) gone - and I put it all down to lots and lots of STP diesel fuel additives (about a 50/50 mix....).

Lots and lots of sooty oily water in the exhaust when on full chat though, and the engine oil has gone black very quickly, but not a problem.

So slowly getting there.

Life is good today.

Cheers,

Keith in Singapore

Hi Keith,
Pleased to see that engine is improving. I'm always told that diesel engines like to be driven hard - that's what they are designed to to. I guess it will also help burn off any carbon deposits in the engine.

Engine oil always goes black v-quickly on diesel engines, nothing to worry about. But it is always worth changing the oil before the boat is laid up or not going to be used for some time as the sooty deposits in the oil do slowly damage the engine (I am told).

Cheers. G

George,

Here just 82 miles north of the Equator boats don't get laid up......sail all year round.....so she'll get an oil change sat on the mooring.

She'll get yanked out for a weeks anti-foul and a topsides respray in November I think....only problem is being in the water for 25 years non-stop means there's also the annual blister popping and filling ceremony...

About to order a new main for 250 quid from Thailand....will tell you what it's like when I collect it.....

Cheers,

Keith in Singapore

250 squids for a main, you could chuck it after a couple of years and still be pleased with the deal!

And here's the quote.....apparently not bullet proof, but at this price....would be rude not to give them a go.

MAINSAIL Top Fully Battened US$ 327.00
with three standard leech battens, Economy
luff 7.91 leech 8.27 foot 2.59, area 12.29 sq.m.
All Battens Included, Loose Footed with
Crew Slug T.B.A.? Boltrope on Foot T.B.A.?
2 Slab Reefs US$ 60.00
1 Flattener US$ 25.00
Insignia both sides US$ 40.00
Sail No's (3 in no.) both sides US$ 30.00

And I get to go to Phuket for the weekend to pick it up......shucks....

http://www.rollytasker.com

Cheers,

Keith in Singapore