Orkney Orkadian. Slowest boat in the Solent

[New Flame]

Hi all. I have recently bought an Orkney Orkadian with a 50 hp Honda four stroke fitted.
Even in calm water the boat strugles to make any speed, with 9 knots flat out it also wallows badly and refuses to track in a straight line.
the boat is kept in a dry stack so the bottom is spotless. Orkney boats state that this is a semi-planing hull and speed with the 50 should be 12 knots +.
Maybe the 50 is just to small for use at sea.
Anyone have any ideas ?
Nick (new flame ).:confused

 

[Coaster]

We had an Orkadian 20 for 4 years. The boat came with a 50hp Honda which was clearly not adequate for sea use. Trying it on a river, where it was located prior to our buying, it struggled to plane, even when very lightly loaded.

So the first thing we did was to fit an 80hp Yamaha four stroke engine. The second best thing we did for the boat was to have a vertical, roll up canvas cover made for the back of the wheelhouse, to keep out bad weather. Other necessary improvements included taking the boat back to Orkney and having a proper fuel tank fitted.

Each year we cruised about 1000M, mostly in the south west and around Pembrokeshire, making passages up to 50M but mostly just coast hopping. The highest speed recorded at sea, on flat water, was 26 knots, but we usually pottered about at 8 knots. We loved the boat but eventually it was too small for our needs. So we now have a larger boat with a stick, as well as a reasonable engine.

If you are going to use a trailer regularly get a multi-roller one. The "standard" trailers are hopeless for recovery. Previously we had a 16' Strikeliner with a standard trailer. That was much, much harder to use than the SBS trailer we bought for the Orkadian.

Good luck.

 

[MarieK]

50hp is absolute minimum for an Orkadian but you should still get over 9 knots, the boat just doesnt have enough power to get over the hump and onto the plane.

Are you achieving max revs? What size prop have you got fitted?

 

[New Flame]

50hp is absolute minimum for an Orkadian but you should still get over 9 knots, the boat just doesnt have enough power to get over the hump and onto the plane.

Are you achieving max revs? What size prop have you got fitted?

When I got the boat it had a 11 1/4 x 13 fitted.
With this prop the motor would only rev to a shade over 4 thou , two thou shy of the red line. But we did see 10 knots (Just)
I spoke to Orkney boats who recomended a 12 1/2 x 9. With this currently fitted the boat is slower but the fuel economy is a lot (50%) better, and now the motor will rev to the red line, although the extra two thousand revs see no increase in speed as this maxes out at around 4.500 rpm.
Swings and roundabouts I guess.
I think I need a bigger motor.

 

[MarieK]

If you can get a bigger motor then do it, it will be a completely different boat with a bit of power to play with. Get max hp for the hull which if its an Orkadian 20 is 80hp.

If you dont go down the new engine route you can try and fit doel fins to the outboard. I had them on an Orkney Pilothouse 20 and it did make her plane quicker.

You should still get more speed out of a 50 though, you could also try raising it a bit on the transom.

Ryan

 

[johnga]

I stumbled across this thread yesterday and recognised the Orkney Orkadian mentioned in Coaster's post!

I bought her in September 2008 and reverted back to her original name of 'Avocet'. I had 18 months of thoroughly enjoyable fast cruising ranging from Chichester to Poole visiting the many creeks and rivers of the Solent in between.

My previous boat had been a Trident Challenger 35 that presented its own problems, not only in shallow waters (with its 5'6" keel) but simply manhandling in the close confines of marinas and harbours, very often single-handed.

The Orkney Orkadian couldn't have been a greater but welcome contrast. Slipping her straight into the water off the SBS multi-roller 4-wheel trailer into the marina at Chichester I was often at anchor on the lovely beach at Bembridge, Isle of Wight, within an hour, or in the tranquil reaches of the Newtown River within 2 hours.

I made a video clip of a trip to Yarmouth, Isle of Wight, followed by Hurst Castle, Lymington and fast run back via Cowes. It goes on a bit! But if you want to see how she planes with the trusty and potent Yamaha 80HP fast forward towards the end of the clip. You couldn't want for much more!

http://tinyurl.com/bo75p4

The Yamaha 4-stroke 80HP F80-BETL lifted the boat onto the plane at around 14 or so knots, depending on the sea state. When conditions were right we enjoyed a delightful 26 knots at full throttle! The secret of successful low speed planing was the correct adjustment of the trim tabs.

She was a beautifully designed, scaled down version of the Seaward 25. I did find her a little small in the end and so sold her in April 2010. She's now in the professional hands of the retired Commander of the Ark Royal (who didn't notice the size difference when viewing, oddly) and she's now near Edinburgh. A great little boat!

I'd be interested to learn what sailing boat Coaster eventually settled on. I'm now looking for a Fisher 30.

 

[Shuggy]

I rather liked your dug. Golden Retriever, presumably?

 

[johnga]

Shuggy, yes he was a Golden Retriever.

'Charlie' by name! He virtually 'raised' our 3 daughters!

I've walked many thousands of miles with him and he's enjoyed (endured? Who knows!) the several boats I've owned.

Regrettably last October, at 17 years old, he was put to sleep. His age suddenly took its toll.

No replacement as yet. But Retrievers are the VERY best in my view!

 

[Mr Wolf]

Even in calm water the boat strugles to make any speed, with 9 knots flat out it also wallows badly and refuses to track in a straight line.
Nick (new flame ).:confused

Pah - I used to dream of doing 9 knots!
Back in the mid '70's my Father had an 21 foot 'Orkney style' boat to which he installed an engine from am Imp married to a water jet drive. The boat was called Wotknot and used to cruise at 4.5knots!!! Flat out was just over 6.

Didn't stop him though - best holiday I remember was 2 weeks in Calais harbour with 4 adults and 4 children all staying onboard!

Didn't put me off boating though - although I do have a fixation with speed and I like my boats to do in excess of 25 knots.

Hope you get your sorted


Richard

 

[davey]

The old tried and tested rules are (1) Displacement hulls such as sailing yachts need about 4 BHP per ton. There is also the problem with hull speed. Its the old K x the square root of the waterline length. K is about 1.3 so a boat with a 25 foot water line length will max-out at 1.3 x 5 knots. Trying to go faster than 6.5 knots will waste energy and fuel, in fact getting an extra half knot to achieve 7 knots will be very costly as the last half knot will consume more power and fuel than the first six and a half!

(2) Planing hulls are a whole different ball game but to lift the boat out of the "hole" needs at least 40 BHP per ton and more is better. Deep V hulls can however have a problem known as "chining". Allegedly this can happen when the boat is going so fast that only the very bottom of the V keel is in the water. At this point the boat can literally fall over! Manufacturers got wise to this problem decades ago so nowadays almost all "Deep Vee" hulls have a flat or rounded end to the V in the last few feet near the stern so "chining" never happens. Decades ago we tried a 100 HP Mercury straight 6 "Tower of Power" on a clone of a Shakespeare Ski-Master. A 28" pitch cupped racing propeller was borrowed and once the boat struggled onto the plane the speed just kept on rising. Observers reckoned that the boat was running at 60 or 70 miles per hour. The boat had no vices apart from its fuel consumption and poor acceleration but it handled very well. The racing prop was quite useless for skiing however as skiing needs masses of tractive-effort.

Some hulls combine displacement mode with planing mode to give the owner two boats in one. There is at least one sailing yacht that has a trick hull and the trick is played by (1) Dropping the sails. (2) Winching-up the lifting keel. (3) Firing up the unusually large outboard motor. Such James Bond features don't come cheap!

Re slow boats, clean off the barnacles and try to reduce the weight. The very small barnacles known as dog-teeth can wreak havoc with engines if they grow on the propeller. In fact I heard about a man who was so exasperated with black smoke that he bought and installed a new engine. The new engine also made black smoke but the problem was those very expensive mini-barnacles! Take care!

 

[scottie]

Six years?

 

[Isle of Mull]

Six years?

How about eight years?
I am replying to this old thread as it may help someone. I read it first when looking for help.
I have an Orkadian 20 and have just fitted a Yamaha FT50 CET High Thrust. It could do with a slightly smaller prop as it will only do 5300 rpm with just me in the boat. The prop is a 13 5/8" diameter 13" pitch. The outboard has fins fitted. At this engine speed it is doing 19 knots. With someone else in the boat it would only rev to 4800 and do 16 knots. I have found it runs faster with the engine trimmed up a fair bit. If you drop it all the way down the bow seems to dig in and slows you down.
I don't know if this is so different to the original poster's boat due to the High thrust??

 

[Shuggy]

If we’re doing monumental and random thread resurrection updates, we now have a Golden Retriever!

Shuggy, yes he was a Golden Retriever.

'Charlie' by name! He virtually 'raised' our 3 daughters!

I've walked many thousands of miles with him and he's enjoyed (endured? Who knows!) the several boats I've owned.

Regrettably last October, at 17 years old, he was put to sleep. His age suddenly took its toll.

No replacement as yet. But Retrievers are the VERY best in my view!

 

[Isle of Mull]

Good to hear. Great dogs.
lets meet here in ten years for another update :¬)