Following a second visit to a Kelt 550 suffering from upwind reluctance, David Harding outlines the changes made to the boat so it can now tack properly

The changes I made to my boat to get it to tack properly

I previously took a trip to Norfolk to look at John and Sheila Taylor’s Kelt 550 and their problems getting the boat to tack.

Their problem was that the boat didn’t like sailing upwind and became unmanageable in a breeze.

Beating against the tide was hard work, and other boats on the river would go straight past.

A boat during a tack on a river

The Kelt 550. Credit: David Harding

This was unacceptable: action was called for.

The issues we found and the improvements we made at the time are covered in this article: Why won’t my boat tack properly?

We achieved a good deal that day, but there were things we couldn’t do on the spot.

I left John with a list of further improvements to carry out over the winter.

With John doing the work, my side of the bargain was to see the effects of these further modifications, so this summer I headed back to Brundall on the River Yare for another sail.

The story so far….

The Kelt 550 is a light, beamy and lively little cruiser in the style of a big dinghy, designed to the Micro Cup rule.

October Dream has a centreplate, but the design was also available with a fin keel or daggerboard.

The problems which made the boat difficult to tack were identified as:

Flat centreplate and rudder:  Nothing can be done about the centreplate – it wouldn’t fit in the case otherwise – but the rudder blade could be improved.

The outboard well was creating a lot of drag:  I suggested John make a fairing plug and put the outboard on a transom bracket for river use.

Under-sized jib: It was about 3ft (1m) short in the hoist. A new jib was needed.

Mast too straight and raked too far aft: More pre-bend and less rake would help.

Rigging too slack: The design of the chainplates meant we had to go easy on the tension, so John would beef them up.

Mainsheet system: It was pulling the boom down too hard. We rigged a temporary alternative that John would convert to a proper system.

John set to work when the boat was out of the water, and I returned this time to find a lot of changes.

Flat centreplate and rudder

A rudder on a boat

The rudder as it was: a flat plate with chamfered leading and trailing edges. Credit: David Harding

Problem:  The rudder presented two challenges. One was that the aluminium blade was flat, except for a chamfer on the leading and trailing edges, which meant that it stalled readily.

The other was that it was unbalanced, with all its area abaft the pivot point, and became unmanageable heavy when the boat heeled.


A diagram shwing a rudder blade on a boat

Action: John sheathed it in plywood, creating a profiled section and, at the same time, extending the leading edge by about half an inch (12mm).

Result: A much-improved shape that helped to keep the boat on track in some lively gusts during our second sail.

The blade gripped much better and also improved control in light airs, though the boat was still prone to stalling on the exit from a tack, especially in light and shifty conditions, because of the flat centreplate.


a rudder on a boat set up so the boat can tack well

The rudder as it is now: plywood bonded to the blade now gives it a proper section and makes it less prone to losing grip. Credit: David Harding

Further action: Despite its improved grip, the rudder was still heavy because its entire area was abaft the pivot point.

The simplest solution would be to modify the stock to allow the blade to swing further forward. This would save changing the blade itself.

The outboard well was creating a lot of drag

Problem: The outboard well was essentially a hole in the aft end of the cockpit sole.

Creating an enormous amount of turbulence, it was probably the single biggest performance-sapping factor.

An outboard well on a boat which is preventing the boat perform a proper tack

As it was: trouble in t’well. This hole must be filled!. Credit: David Harding

Action: On our sail last year we wedged a plastic picnic box into the aperture as a temporary fix.  That made a big difference.

A plastic box in an outboard well of a boat to try and make the boat tack properly

Last year’s improvised instant improvement: picnic box to the rescue. Credit: David Harding

The plan was for John to make a removable fairing plug but, after he started, he realised that a much quicker way to ensure a smooth hull was simply to glass in a piece of plywood flush with the bottom.

An outboard well on a boat filled in

John’s solution: glassing a piece of plywood into the bottom has created a flush finish to the hull…Credit: David Harding

It could always be cut out again to restore the well at a later date.

A petrol tank in a sealed up outboard well

… it also made a handy locker for the petrol tank…Credit: David Harding

In the meantime, the outboard lives on a transom bracket and works perfectly in the flat water of the river. It’s also a lot quieter outside the boat.

A outboard well on a boat covered up

… that can be covered to leave a smooth cockpit sole. Credit: David Harding

Result: Now the brakes are off! The increase in boat-speed is dramatic.

It was like cutting loose a bucket that had been dragged from the stern.

A outboard on a transom of a boat

It wouldn’t be so good out at sea, but in the river the outboard is fine on a transom bracket. Credit: David Harding

Further action: None needed (unless John or a future owner wants to use the well again).

Rig and rigging

The forestay was too long and the rigging too slack

Problem: It was a case of multiple, inter-related problems with the rigging.

A forestay set up on a boat which is preventing the boat from tacking properly

Forestay: What a mess! A forestay should never be attached to the stemhead like this. Credit: David Harding

To set enough pre-bend into the mast to match the luff-round in the mainsail, we needed more tension in the cap shrouds.

A forestay on a boat which is allowing the boat to tack properly

Forestay: Now a link tang and bottlescrew have replaced the shackles: easier to adjust and stronger too. Credit: David Harding

We couldn’t tension the caps as far as necessary because the forestay was too long as a result of a mishmash of shackles attaching it to the stemhead.

Chainplates on a boat which holds the mast up

Chainplates: Originally the chainplates, especially on the starboard side, were misaligned, forcing a bend into the bottlescrews. Credit: David Harding

That in turn meant we had insufficient thread left on the bottlescrews.

Chainplates on a boat

Chainplates properly aligned and toggles on the bottlescrews to make sure there’s no unfair loading. Credit: David Harding

We were also concerned by the poorly-aligned chainplates that were bolted through the flange of the hull-to-deck joint with the load spread only by small washers. Caution seemed prudent.

Action: Last year we wound down what tension we could (and dared) on the bottlescrews.

A folded up sail on a boat

Rake: Too much rake: this was about
24in (60cm). Credit: David Harding

Over the winter, John realigned the chainplates, spread the load with a strip of stainless steel, fitted new bottlescrews complete with toggles and replaced the forestay’s shackles with a link tang for strength and easier adjustment.

Result: Greater integrity in the boat’s rig allowed us to increase the cap shrouds’ tension appreciably, leading to extra forestay tension for upwind performance in a breeze (more speed and better pointing combined with less heel and weather helm).

A winch handle handing from a boat

Rake: Less rake – but still too much. It’s now about 18in (46cm), so the forestay can be shortened further. Credit: David Harding

The extra tension should also have increased the pre-bend in the mast, which was our principal objective, but getting it to bend enough – despite the slender section – proved impossible, even with the lowers slackened right off.

A diagram showing the effect of increase mast rake on a boat performance

Increased mast rake reduces the deflection of the cap shrouds by the spreaders and, therefore, the extent to which the spreaders push the middle of the mast forward to induce pre-bend.

Before tensioning the caps further we shortened the forestay by moving the pin in the link tang down a couple of holes, both to make sure we would have enough thread on the bottlescrews and to reduce the excessive rake.

Further action: We could have taken the pin down a few more holes to reduce the rake still further. Reducing the rake also moves the hounds forward in relation to the chainplates, increasing the effect the swept spreaders have of pushing the middle of the mast forward.

A diagram showing the effect of rake on a boat's sailing performance

With the mast more upright, the angle of deflection is increased so the spreaders work more effectively

This should increase the bend to help match the 55mm of luff curve that Kemp built into the mainsail.

A problem was that one of the new bottlescrews had seized, so we had to replace it with an old one that John had on board.

Mainsheet system

It was exerting excessive vertical pull on the boom

Problem: Originally the sheet was a 4:1 purchase from the boom to a strong-point on the cockpit sole.

A man in a boat trying to make it tack in a river

As it was: the centre sheet detracted from the sail shape and cluttered up the cockpit, and made it difficult to tack. Credit: David Harding

This exerted too much downwards pull and closed the leech of the sail while not bringing the boom close enough to the centreline.

Action: During our outing last year we rigged up a temporary transom bridle.

A makeshift bridle on a sail to try and make the boat tack properly

Our makeshift bridle last year opened up the leech of the sail, allowed the boom to be sheeted closer to the centreline and created space in the cockpit. Credit: David Harding

John has now refined the bridle and led the sheet along the boom to a ratchet block.

Result: Our makeshift bridle got the mainsail working much better and created a clearer cockpit – even with just two people in the cockpit, the centre sheet got in the way.

A bridle on the rigging to make a boat tack properly

As it is now: the bridle in its latest form and with the sheet led along the boom to a ratchet block. Credit: David Harding

The new bridle, with proper blocks and line rather than those I happened to have in my sailing bag at the time, works even better, while the ratchet block reduces the load transmitted to the hand yet still allows instant adjustment.

Further action: Other than some very minor tweaking here and there, the system is sorted. It works beautifully

The under-sized jib

Problem: The jib we sailed with last year was way short in the hoist, the head being about 3ft (1m) below the top of the forestay.

A boat with sails up sailing in a river

Originally the jib was far too short in the luff…making the boat difficult to tack. Credit: David Harding

This wasted a lot of area and drive and probably contributed to the weather helm too.

Action: Kemp Sails made a new, full-hoist jib that maximised the area.

Result: Luff length is important with headsails and the new sail undoubtedly made a big difference in pointing, speed and balance.

A boat with a new jib performing a tack up a river

… but has now been replaced by a new one that’s full-hoist, so the boat can tack properly. Credit: David Harding

Further action: As far as the jib is concerned, it’s job done.

All John realised he should have asked for is a window in the foot.

Changes to make my boat tack properly: Cumulative effects

Short of making one change at a time and measuring the effects of each, it would be impossible to say which made the biggest difference.

We suspect the outboard well had the greatest effect on straight-line boat speed, particularly off the wind. It was noticeable how quickly the boat accelerated in the gusts with the turbulence now eliminated, helped by the drive of the new jib.

During our tweaking, we happened upon a Yeoman (a 20ft/6m keelboat that’s popular and widely raced in East Anglia).

Unable to pass up the opportunity to pace ourselves against a well-sailed boat – even one that’s longer and almost certainly faster – we gave chase as we short-tacked up the river.

Not surprisingly, the Yeoman gradually pulled ahead but we hung in there pretty well and were happy with the way we were going.

Changes to make my boat tack properly: conclusion

Until last summer, October Dream was lacking performance all round, hopeless at short-tacking and unmanageable in anything more than about 14-15 knots: she would heel over, round up into the breeze and refuse to be tamed.

On our outing last year, we had light conditions but made changes that helped her performance both then and, as we hoped they would, in a breeze too.

This time, although the wind was up and down, we had a spell when it was gusting to 16 or 17 knots.

Continues below…

The boat was still heavy on the helm because of the unbalanced rudder, but keeping her under control, short-tacking up a narrow river and sailing reasonably fast was no problem.

She was a different boat from the one she had been just over a year ago.

While there’s still scope to improve the mainsail’s shape by inducing more pre-bend in the mast, to reduce the rake, to balance the rudder and, while we’re at it, to make the kicking strap more powerful and quicker to adjust, it’s 85% job done.

Faced with a wayward and temperamental boat that wouldn’t tack properly, as October Dream had been, many owners would have simply given up.

Instead, John and Sheila made all of the suggested changes so they are now more confident when sailing October Dream, and they enjoy it more.

Enjoy reading The changes I made to my boat to get it to tack properly?

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