MR : Tuning Older Boats

Tuning Older Boats

Dan Alsop

My travels as Training Officer have left me in no doubt that the favourite subject for owners of older boats is tuning. It would seem that the freedom of experiment allowed by the Merlin rules is a major reason why people buy old Merlins in preference to one - designs.

Getting Advice

I am often surprised at the number of you who do not have a copy of Dick Batt's excellent Merlin Rocket Tuning Guide which covers all ages of boat. Dick kindly allows us to reproduce his guide for training purposes and I do commend it to you. Get a copy from www.battsails.com.

Owners of contemporary boats should simply follow the lead set by the boats at the front of the fleet. Buy the same kit and ask about setting it up.

1. Get the timing right - ie., don't pester people when they are rigging/packing up. Breaks between races are best, or during the evening social.

2. Write down what you are told straight away - even if you don't understand it or disagree.

3. Don't ask the same person the same question more than once, especially if you have ignored their previous advice!

4. Don't rely on the advice of one person. Keep asking, comparing, thinking, discussing, questioning.

Older Boats

For those of you with older boats life is much more difficult. Dick Batt's tuning guide is understandably targeted at optimising the sails on an existing boat / rig. If you want to modernise the rig or even restore the boat to its original specification, advice is hard to come by.

In this article I put forward my thoughts for those of you who have boats boats with high bow tanks and no bulkhead and who want to get the best possible performance without modifying the hull. The change to low tanks / bulkheads came about in 1980 at around sail no 3200. In subsequent issues I will talk about putting new rigs on old hulls and my views on what really matters and what doesn't where boat speed is concerned.

Getting The Most Out Of A High Bow-Tank Hull

High bow-tank boats without a bulkhead at the aft end of the foredeck are very flexible compared within those built the modern way, especilly as very few of them are less than 17 years old. Just watch the leeward shroud when you are tacking to windward in a "sitting-out" breeze - it will be quite slack. Setting up the rig tighter beforehand will make scarcely any difference, all you will be doing is closing the boat up like a clam shell; remember the class folklore which speaks of hard-driven Merlins splitting down the middle in the bad old days!

But to sail with too much jib luff sag is death to windward performance. On a modern stiff boat the jib luff is tensioned to the required value by tightening the shrouds. So on an old boat where you are unable to tighten the shrouds the only way of keeping the jib luff tight is to sail with loads of mainsheet tension (the kicker has no effect, being anchored to the foot of the mast). By contrast todays hoop is designed to achieve exactly the opposite effect! So, in old boats it is absolutely essential to use a traveller. For those of you wanting to know more about this, Lawrie Smith's tuning book is excellent and explains the theory, but not in a Merlin context.

I cannot over-emphasize the importance of this point, having once converted my own Smokers Satisfaction 2994 and completely wrecked its previously stunning upwind performance. Restoration of the traveller instantly put matters straight. Only then did I recollect the words of Jerry Rook, its first owner: "The way to make these boats go to windward is to pull the mainsheet as hard as you can: then put your foot against the centreboard case, and pull it in a bit further. Do everything you can to avoid letting it out. If you can't keep the boat flat let the traveller down a bit, but no further than the middle of the boat (single carriage) and whack on the cunningham. If you still can't keep the boat flat - get a bigger crew."

This of course is completely contrary to modern thinking but explains why these boats were sailed with 23 - 26 stone in their heyday.

The mainsails were cut to cope with these very high sheet tensions without hooking the leech, lots of luff round to accommodate the inevitable mast bend and plenty of fullness to carry the fatties down the reach. We are all aware of the benefits of a parallel slot, so because the mainsails could not help but set like a "barn door", the jibs were similarly shaped to allow hard sheeting and the farleads were set wide to avoid backwinding the mainsail. Masts were heavier in section both to cope with the fatties and also because the looser shrouds could not exercise the same control via the spreaders. This is why putting modern sails cut for a "hoop" rig on one of these boats will not work well (unless the wind is too light to matter).

SUMMERY - If You Don't Want To Stiffen Up The Hull

1. Keep or restore the traveller
In an old Merlin the traveller does not need to be full - width, and twin carriages with a bridle (or even a low travelling hoop, 470 style), will take away the need to fiddle with the thing every time you tack.

2. Keep The Old Mast
Alpha Plus and Beta Minus were the business: today the M7 is probably as near as you'll get. Whatever you do don't use an M1 or a Kappa - even if it doesn't snap it will bend too much.

3. Have Sails Made To Suit
Preferably by a sailmaker who made sails in the late 70's and who has the patterns.

4. Make Sure You Have Enough Pudding On The Side!

5. Sheet Hard And Use Plenty Of Kicker.

DAN ALSOP

TUNING TIPS FOR OLDER BOATS - Part 2

Deck Stepping Old Boats

I wrote before about getting the best out of an old boat without converting to a deck-stepped rig. I have been very encouraged by the amount of interest the notes generated. However lots of people with old boats have gone on to ask me whether they should convert to a deck-stepped set-up so here are my thoughts.

Why deck step?

The deck stepped system naturally followed on from the move to raking rigs. These had been developed because the top guys wanted to sail light (for downwind speed in light and medium conditions). To cope in a blow they had to use softer masts (to match the reduced sitting out power) and find a way of de-powering more effectively - this was done by raking the mast back.

However it was realised that raking back a hog stepped mast progressively reduces the spreader effectiveness, which had become more important with the move to softer masts. Furthennore the loadings imposed on the light masts by the mast gate were resulting in lots of breakage's. To avoid these problems deck-stepping was adopted.

Advantages

The mast can be raked back to de-power without affecting the spreader geometry.
The mast is shorter and thus lighter.
The absence of stress at the mast gate enables a thinner section to be used without damage. This not only saves even more weight but more crucially allows the section to be selected which takes on the correct amount of extra bend as the wind increases. This relationship is known as gust response and is crucially important because it de-powers the rig automatically without the crew making adjustrnents.

However like most good things in life there are problems.

Deck stepped masts are easy to drop on your competitors' heads when rigging and de-rigging!
They tend to adopt a reverse bend on a tight spinnaker reach - hence the adoption of pullers.
To control the set-up complicated systems are needed, not only adding expense, but also liable to distract crews from the other aspects of racing they should be thinking about.
A stiff hull is essential so that the shroud tension can be accurately controlled - necessary for the spreaders to work properly. Without this the smaller masts would over-bend or even break. This is where old boats can run into problems.

How should you go about it?

Ensure your hull is stiff enough. If it isn't you will be wasting your time and money.
lf your boat has a high bow tank, get the boat modified.

There are basically two ways forward. Either install what has become the standard low tank/full bulkhead system, or add a space frame.
Any of the established Merlin builders will be able to undertake this work, but if you want to DIY the first thing to do is to look at as many converted and modem boats as possible and talk to the amateurs and professionals who have done the job before you. Go to a Silver Tiller event with a camera instead of your boat!

Choose the new rig

Try to avoid the temptation to buy unproven kit in the forlom hope of pulling a fast one over Mr Whitworth. lt hardly ever works! (Ed. Anybody want to buy a wing mast???)
Study the front runners and ask them about their masts, sa�ls and settings. You will find a greater consensos than you might expect. Don't forget that the shroud bases vary between different designs, and even between similar designs built by different builders. So don't take spreader offsets from the mast as gospel. The amount they deflect the shrouds from a straight line is a more reliable guide.

Using the New Rig Get sailing!

With all the new strings there is so much to leam, and so many ways of slowing yourself down! Particularly if you do not have a handy trial horse to tune with, come along to the Class Training Event next Spring where top helmsmen will be available to guide you.

Until then, here are a few key tips:

1. Set the rake using the jib halyard, and have clear marks. Don't rake progressively - leave well alone until you are overpowered most of the time.
We start to rake in about Force 3/4 and I then find it does not need much more wind for us to need full rake. The idea is to rake just enough to ensure that you can keep the boom hard in for most of the time (keeping the boom on centreline is essential for good pointing).

2. Adjust the shrouds to keep the lee shroud just tight. This means tightening them as you sit out harder as well as when you rake, so you can't really mark the settings.

3. Set the lowers to suit the rake. Have an equivalent mark for each of your jib halyard settings.
Don't overdo the lowers - check on shore with the main up and normal rig tension - the mast should have a sweet curve and not be straight below the spreaders.

4. The crew should do the strings, even if the helmsman calls the shots. Mark the strings to make life easy.

5. Remember the puller, if it's windy enough for the crew to sit out. But don't leave it set on the beat if your spinnaker pole can get under it - if this happens a quick tack will probably snap the pole like a rotten carrot!

Conclusion

If you need convincing and haven't tried sailing a Merlin with a modem rig in a strong wind, do so - you will be amazed how manageable these boats have become.

Finally, don't rake your mast below the horizontal, as we did.

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