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Old 16 June 2008, 06:35   #1
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5.4 searider engine height.

went for a spin in the sr5 for the first time on sunday, all went OK and i didnt sink! only problems a loose rubbing strake and a fuel leak.
managed 30Kts in flat water(no tachofor revs yet), 2.5 up with 44l of fuel. engine is a yamaha 80. prop is i think 17.25x 13? if i remember off the top of my head. didnt seem to lose bite in tighest full power turns, engine is sat right down on the transom.
How much speed am i likely to gain raising 1 hole on the transom? is this likely to cause any problems? where does everyone else have their 80/90 yams sat on searider transoms?
Nos rekons 30 isnt bad, but i want to go faster!!! how much extra for the investment of a SS prop? in terms of 18-20Kts cruising economy ant extra speed top end?
cheers.
M
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Old 16 June 2008, 15:21   #2
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Probably 13.25x17p prop size-you might be able to get away with 19p.

You might get a couple of knots more if you raise the engine one hole but it will cavitate on full power turns. Mine does.
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Old 18 June 2008, 06:39   #3
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Rpm?

Might want to get a tacho to see what RPM you are pulling before investing in props or moving the engine.

On my 5.4m with 90hp 2 stroke Mariner I had the engine right down and a 20" SS prop. I reckon the engine could have come up a hole but sold the boat before I got round to trying.

Would agree that a 17" prop on an 80hp would be a good starting point.
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Old 18 June 2008, 22:48   #4
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are you running a 20" or 25" motor?

im running a 20" 75, but replacing it with a 90. i THINK i need a 25"
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Old 19 June 2008, 03:19   #5
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Quote:
Originally Posted by mcinfantry View Post
are you running a 20" or 25" motor?

im running a 20" 75, but replacing it with a 90. i THINK i need a 25"
If you put a 25" shaft motor on there it'll be too deep. 25" shafts weren't made when Seariders came into existence.
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Old 21 June 2008, 07:49   #6
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Just try to move the engine one hole up, if you invest in a SS prop you're able to lift the engine even more and your rpm and speed will get higher also.
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Old 05 July 2008, 17:33   #7
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Hi there ,
i will finish my SR 5,4 this month. I have a 75 HP Yam with a light tune up to ca 90HP.
I have a new transom fitted to it and now the caviation plate is 1 inch under the keel and a offset of 1,5 inch to starboard. Should it be more offset upto 2inch?
Do you run the engine with the caviation plate in line with the keel?

Greetings from Germany
Mike
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Old 05 July 2008, 22:37   #8
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Quote:
Originally Posted by mike-stgt View Post
Hi there ,
i will finish my SR 5,4 this month. I have a 75 HP Yam with a light tune up to ca 90HP.
I have a new transom fitted to it and now the caviation plate is 1 inch under the keel and a offset of 1,5 inch to starboard. Should it be more offset upto 2inch?
Do you run the engine with the caviation plate in line with the keel?

Greetings from Germany
Mike
no, i think thats too low. i think 1.5 will be fine. im 3.5" above the keel, but may drop it 3/4" (1 hole)
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Old 06 July 2008, 02:56   #9
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no, i think thats too low. i think 1.5 will be fine. im 3.5" above the keel, but may drop it 3/4" (1 hole)
Hi again, wrote :"above the keel". Does it mean the distance between keel and caviation plate really above, or under the keel??

Greetings Mike
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Old 06 July 2008, 09:55   #10
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Originally Posted by mike-stgt View Post
Hi again, wrote :"above the keel". Does it mean the distance between keel and caviation plate really above, or under the keel??

Greetings Mike
sorry. i think 1.5" starboard is fine. it seems ok for me.

im 3.5" above the keel. i am going to lower it back to about 2.75". i liked it there best.
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Old 06 July 2008, 11:23   #11
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Hi again, you will be the only one, who has the caviation plate above(over the keel.) The prop will soak air in sharp corners. 3,5 inch below will create a drag of your gearbox. How fast is your boat with this setup?

Greeting Mike
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Old 06 July 2008, 11:37   #12
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Originally Posted by mike-stgt View Post
Hi again, you will be the only one, who has the caviation plate above(over the keel.) The prop will soak air in sharp corners. 3,5 inch below will create a drag of your gearbox. How fast is your boat with this setup?

Greeting Mike
well, as the only one who has actually taken the time to try it, and the only one who will post it, at 2.75" ABOVE THE KEEL and 1.5" starboard, the boat runs 42 to 43mph with 26 gallons gas, 500lbs of people on a 17" propeller, and its center console, leaning post, trampoline top with 2 ice chests..... i dont have to trim it at all in sharp turns at that height..... it drags HORRIBLY level with the keel.



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Old 06 July 2008, 16:39   #13
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I run the anti cavitation plate 6 inch above the keel.

Positive effects:
-the boat turns way more rpm than with the engine lower = much more speed;
-the boat chinewalks less.

Neutral effects:
-the exhaust is above the water = a few times louder engine;
-the prop throws a huge spray, (in my case about 9 feet high and 40 feet to the back, with only 75hp).

Negative effects:
-you need a SS prop that is capable of running in surface conditions;
-there will be much more torque on the steering system, so you need a stronger steering system;
-more load @ the stern, so maybe you have to reinforce it;
-in most cases you need a lift in order to mount the engine higher;
-often you need a low waterpickup in order to have enough cooling;
-so it's much more expensive than a lower engine height.
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Old 06 July 2008, 17:07   #14
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Quote:
Originally Posted by mcinfantry View Post
well, as the only one who has actually taken the time to try it, and the only one who will post it, at 2.75" ABOVE THE KEEL and 1.5" starboard, the boat runs 42 to 43mph with 26 gallons gas, 500lbs of people on a 17" propeller, and its center console, leaning post, trampoline top with 2 ice chests..... i dont have to trim it at all in sharp turns at that height..... it drags HORRIBLY level with the keel.



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JESUS.... I did not realise you had all that stuff hanging off it. I would say you are pretty much spot on for speed now I have seen the pictures.

That canopy probaly costs you several knots on its own...

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Old 06 July 2008, 18:46   #15
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JESUS.... I did not realise you had all that stuff hanging off it. I would say you are pretty much spot on for speed now I have seen the pictures.

That canopy probaly costs you several knots on its own...

actually the canopy cost zero in speed, i ran it for the first two tries without!
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Old 18 October 2008, 08:54   #16
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What engine length would you reccomend for this early 90's searider

20" or 25"
going with 90hp
Thanks
ab
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Old 18 October 2008, 08:55   #17
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What engine length would you reccomend for this early 90's searider

20" or 25"
going with 90hp
Thanks
ttp://pictures.aol.com/ap/singleIma...v4xQp5Fd3Ig%3D
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Old 18 October 2008, 18:00   #18
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20".
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Old 28 November 2012, 13:26   #19
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Hi

I will put an Suzuki DF90 on my SR5. Anyone who can tell which original prop size I should ask for.
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Old 27 March 2013, 03:47   #20
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Quote:
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Hi

I will put an Suzuki DF90 on my SR5. Anyone who can tell which original prop size I should ask for.
Did you put the DF90 on ?? What is your experience ???
Thanks .
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