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Discussion Starter #1
Age old question - all opinions valued - I have a late (one of the last) Orkney Strikeliners 1997 with a 15hp Honda e/start with remotes. Everything is in very very good condition and currently I am getting about 9kts two up with kit. The thing is I want more. The boat is barely getting onto the plane so the motor tends to have two settings - tickover and flat out. The boat is rated to 25hp and 22knts empty I suspect - Orkney tell me that the later Strikeliners were re-inforced across the boat towards the transom and will easily cope with 30hp a' la 520. I am prepared to buy a new motor ideally I would like to spend £2000 but this is going to get me a two stroke which is light and peppy or I can get a new Suzuki 30 4stroke ptt for £3100 plus fitting which seems pretty good just more than I really want to spend and £1100 buys a shed load of fuel and oil. Nice dilema eh? I can get a Tohatsu 30 4stroke for just under £2600 however I have heard different stories, some say they are Suzuki's The agents deny this - some say they are cheap and you get what you pay for. I know that Mariner and Mercury are the same - I know little about Yamaha.
I am keen to fit a 30 as it is possible that at some point I may get a 520 and only want to buy a motor once - This does mean that I will have a very good Honda 15 es ls with alternator and remotes for sale. So OTY
Regards Steve
 

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Tohatsu is a rebadged Suzuki 4 stroke, if you have a dealer near you they are well worth considering. You have a semi planing hull there so no matter how much power you hang on the transom you will not get it to go at more than hull speed. In other words you hang a 60hp on the back and it will not do more than a couple of miles an hour more than it's designed speed. The hull needs to be a lot flatter on the water to get it to plane, with the rounded section you have it is slow hull but stable, it is a trade off.

I would personally go for the most economical, I have done 2500 miles in mine in 3 years, I have a 4 stroke, the most economical at the time. I use about a litre a mile so double the fuel consumption and the difference betweeen 2 and 4 stroke dissapears pretty quickly.
 

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Discussion Starter #3
Hi Chris - thanks for the reply - what I am looking for is more speed than the motor- frantic 9knts max that I am getting - I would be happier with 12 - 15knts knowing that the motor is understressed. At the moment I am running flat out everywhere. Also I get the feeling that with a bit more poke the boat will climb out of the hole, possibly allowing me to throttle back a tad. At the moment it is basically a displacement hull, 9 knts is the max speed 7 is a more realistic average. The main reason for going to a 30 over a 25 is that if I go to a new motor now I will probebly keep it for a while. So if next year or the year after I decide to update the hull I don't have to shell out on a motor as well. Back to the Tohatsu thing people say that it is the SAME motor as the Suzuki but is this the case for the four strokes or just the two strokes. The Tohatsu 30 is a 3cyl 492cc engine weighing 68.5kg - the Suzuki is 3cyl 597cc unit weighing a whopping 96kgs.
Anyone lived with a Strikeliner and has engine preferences / experiences as I have also heard that the boat has peculiar handling characteristics when planing with a tendency to 'Fall over' ??
 

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I think you need to read Chris's reply again as Chris says your boat is not designed to plane it will not plane it has a maximum speed which no matter how big an engine you fit on, it will not go over so you need to get an engine that will give you this and not rip the transom off.. 4 stroke engines are heavier than 2 stroke.
 

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Tohatsu make their own 2 strokes and buy in Suzuki for their 4 strokes.

Did you ever skim stones as a kid? You looked for the flattest stone to get the most skips on the water. A round stone was useless. The flat stone was planing on the water, the round stone displaced the water. the more power you put into the flat stone the further it went as long as it stayed flat to the water. The round stone just made a bigger splash.

It is exactly the same with a boat, flat bottom dories will plane easily with little power but they tend to slam and be skittish when they are travelling quickly.

A yacht has a lot of rounded hull in the water, it has to push that water out of the way to move, displacement hull. No matter how much power you put in it will not go faster than it's designed speed. They are stable hulls and can take much worse weather than a flat hull. They generally have a small hp engine turning a large prop slowly. If you had a big engine torning a small prop quickly the boat would go nowhere due to the prop spinning in its own cavitiation.

You have a hull that is a compromise, it has the stability of a displacement and some of the speed of a planing hull, but the faster you drive it through the water the more unstable it will become as more of the hull is out of the water and it doesn't have the flat bottom of a dory to spread the load out.

I think the power - speed is a square relation on your hull, in other words to double the hull speed you need to square the engine size. Say a 4hp engine gave you 4 knots, to do 8 knots you would need a 16hp. If you put a 30hp on the back of your boat you are not going to double the speed, what you will have is more flexibility and you will not be flat out all the time. You will have to build up the power slowly or your prop will cavitate.

Strikeliners were designed to be a stable slow speed boat that can be pushed along with a small economical engine. At a guess, if you put a 30hp on the back with 2 of you and all your fishing gear I think your top speed would be somewhere 12 and 15 knots, but that it only a guess. Do you know anyone with a larger engine that you could borrow and try it out?
 

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Discussion Starter #6
So am I totally barking up the wrong tree? Sanctury says that the boat is not going to plane with any motor - the Strikeliner that passed me in Falmouth bay last Sunday looked to be planing and the various 520's that I have seen seem to be cutting along at a tidy rate. My boat definetly rides and steers better at 9knts than it does at 5knts. If I get Chris' anticipated 15knts with a 30 that would be satisfactory as it would halve my transit time and allow for more fishing time. Also the motor would not spend the majority of it's time being caned. The main reason for my post related more to engine manufacture, Tohatsu quality and 2 versus 4 stroke. Steve
 

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Tohatsu 2 stroke are the only engine that is warrantied for racing, have a look at Zap Cats, most use them. They are virtually unbreakable. The 4 stroke is a Suzuki rebadged so there is some £ to be saved there and Suzuki make a good engine. For some reason Nissan called their engines Tohatsu here, the parent company is Nissan, there are not many dealers about for them but if you have one locally I would go for it. They are both reliable engines.

The 4 stroke is heavier than the 2 stroke so that is a factor on your decision especially with Tohatsu as they make a particularly light 2 stroke in most of the power ranges.
 

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I have just sold my Strikeliner 16+. It had a Suzuki 30hp 4 stroke on it. The handling was a bit "strange" if full throttle used, so I got it on the plane & then throttled back slightly. My personal feeling is that a 25 would be the best. According to my gps, this cruising speed was 18 (can't remember if this setting was knots or mph - doh!!). The Suzuki is a very economical, reliable engine.
Regards
Alan
 

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Discussion Starter #9
Thanks Alan - It was some first hand experience that I was after as it is not possible for me to try out a motor before buying - I notice with mine that the quicker that we go the smoother the ride gets and the better the steerage. Obviously I am not looking to ski behind the boat just looking to keep the boat and motor comfortable at about 12-15knts. You did not notice the extra weight and power of the Suzuki trying to rip your transom off then ? Regards Steve
 

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Discussion Starter #10
:D Decision made - I have just bought a 3hour old 25hp Tohatsu 4stroke - I will let you know how it goes. Many thanks for all the replies - I fancied the Suzuki but the weight (96kg) put me off a bit - let alone the extra dosh, also Chris' confidence in the brand helped as well as the fact that the 25 is a detuned 30 - which sort of appeals. - Now - where's my wakeboard ;) !!! Steve
 

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I too would be interested to hear how you got on with it. I have recently bought the same setup. i.e a Strikeliner 16+ complete with Tohatsu 25hp fourstroke.
 

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Greenheart and Toonfireman, I fear you might wait some time for your answer - the OP hasn't posted on here for over three years - this is a very old thread that's suddenly resurfaced.

Probably more likely to get an answer by starting a new thread.
 

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Greenheart and Toonfireman, I fear you might wait some time for your answer - the OP hasn't posted on here for over three years - this is a very old thread that's suddenly resurfaced.

Probably more likely to get an answer by starting a new thread.
Just in case they don't......
There is a lot of rot spoken regarding Orkney hulls , where people assume that they are all slow displacement boats of traditional underwater lines.
They do some small dinghies that are, but everything of fourteen foot or over, with the exception of the Longliner and Fastliner 16, is a planing hull.
They take a bit of setting up, and the load distribution must be kept around the bench seat amidships, but they absolutely fly for what they are.
We had 23 knots, rising to a tad under 24 knots off Bradwell with the Flying Aardvark on a flat sea.
That's with a 20 hp Yamaha two-stroke, two blokes aboard, and kit, in a fourteen foot Coastliner.
It does around 10 mpg at slightly more sensible speeds.
Not overloading them, and balancing the load both laterally and fore-and-aft is the key to getting them to really stomp on as they should.
Cheers,
Davey.
 

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these articles may be of some interest with regards expected performance from a strikeliner.
the below is taken from fishingfilmsandfacts.co.uk

To simplify things, lets look systematically at the good and bad points of each hull type in turn. When I first started fishing, the traditional displacement hull still reigned supreme. A few of the newer designs were beginning to make an appearance which I was reliably informed would not stand the test of time. You can’t beat a true displacement hull I was told. Today you would struggle to find one. As the name implies, they ride through as opposed to over the water, displacing it (pushing it away) as they power forward creating a lot of drag which in turn limits the top speed of the boat. When the maximum speed is reached, which is usually around 6 knots, that's it. The performance level of these hulls is governed by the laws of physics which state that the maximum achievable speed of a displacement boat is 1.34 x the square root of the waterline length. The square root of a 16 foot displacement hull is 4, which multiplied by 1.34 gives a top speed of 5.36 knots. Putting a bigger engine on the back will not increase that speed. But what it will do is make the boat less safe. Too much weight and thrust at the back will cause the bow to rise reducing stability under power, making it more likely to turn over in rough conditions.

“But they ride so much better than the newer designs in lumpy conditions”, was another argument put in their favour. Don’t believe a word of it. Their best, which comes at low speeds into a lumpy sea, can be matched by many of the newer designs, and due to their semi circular shape, despite having a keel, they roll like a pig in a beam (side) on swell. For me, they were only the best when there was nothing else on the market to compete with them. Now there is plenty of competition. Some innovative thinking, primarily from Orkney Boats, has brought the displacement concept into the modern world. Orkney's faster traditional looking models are in actual fact semi-displacement boats created by flattening the rear half of the hull to give the front end lift and increase its pace. I fish fairly regularly from the 19 foot version and have been out in some particularly nasty conditions. They give a pretty good ride but do roll quite a bit when out in a beam on swell.



http://www.fishingfilmsandfacts.co.uk/voutfitchoice.asp
 

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Hi.
Ok to help you Out try this ok.
Have you got a long shaft on a short shaft hull? it causes drag. stops correct planning.

So if your mesurment is correct, but still not good.

Remove your 25hp outboard. now Replace it 2" inches higher than normal and bolt it on?
becuse your hull is not going to max speed the hydraulic action of water will slow you down. Raise the outboard 2" Inches loses the drag at both low rev and high ok.
a rev counter would help. but you should beable to tell by Ear alone the revs.

Next balance your little hull out tidy.

remove all forward weight to the middle of the hull, then also as close to the centre line of boat as possible, this will help lateral roll later on.

Balance =so when your not in it it should lean just to the opposite side to where you steer from.
Same now applies if you intend to take out a passenger.
correct balance = better speed = better economy also.



Angle of engine. You have a few angle setting on the rear of the engine. These give you trim. you want to trim out the engine, so try out the furthest from boat first,test it then bring it back in a bit. bring the Bow/nOse up ok when moving along. not to high with that ajustment or she will bounce, known as porpoising. go one back or down from porpoiseing.
So one setting back from the bouncy one will surfice ok.
if ever she bounces again on this setting add a little weight back to front.

Now your boat should do 25plus.
forget the bigger outboard.

I had an 17.6ft Orkney doing 18+with a 15hp suzuki ,4 stroke tho
It was only becuse i wanted heating, more cabin space to make tea n crumpets and another 20mph top end that i got rid of it.
But it was real fun to blast it about the bay. And it could take some rough also.
10 oouta 10 for Orkneys
 
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