Grajan
Well-Known Member
Just purchased an Orkadian 20 with a Yamaha 60 DET four stroke, I have been surprised that this engine will not get her over the "hump" could it be prop size?
Orkadian 20
- Thread starter Grajan
- Start date
ChrisE
Well-Known Member
Not sure, I have an Orcadian 23 with a 115hp and this does not plane happily and am fitting trim tabs to it at present in an attempt to bring the nose down. The craft is supposed to have a top speed of 22knots and the best we recorded so far is about 17 and that on a flat calm with not too much weight up.
I'm told that the problem is that the o/b versions have so much weight at the back that the hull form doesn't easily plane.
I'm told that the problem is that the o/b versions have so much weight at the back that the hull form doesn't easily plane.
N
NJMcK
Guest
We have an Orkadian 20 which we've used extensively for 3 seasons. If you have any particular questions do let me know.
When bought the boat she was 4 years old and had been little used. She came with a 50 hp Honda which we regarded as underpowered for coastal cruising. We sold the Honda and fitted a new 80 hp Yamaha four stroke.
We have found that prop size makes a significant difference to performance and economy. The eventual choice for us was 13 1/2 " diameter x 15 " pitch.
Whether or not a 60 hp engine will suffice will depend on your use of the boat. In rough western waters we find the larger engine very useful. (I realise that Orkney state the hull is linited to a 75 hp outboard but Yamaha don't do one. We looked carefully at the alternatives and concluded Yamaha made the best engine for us.)
In flat water we can get up to 26 kts at 5500rpm, but that's noisy and boring. We usually travel at 12 - 15 kts in reasonable water or 18 - 20 kts if there is a reason to hurry. Alternatively, if it's very rough, the boat is excellent at 6 - 8 kts.
We also have hydraulic trim tabs. They are quite useful in the 9 - 15 kts range, but very unhelpful at higher speeds - one can dig in suddenly, causing the boat to list alarmingly.
I hope this helps.
When bought the boat she was 4 years old and had been little used. She came with a 50 hp Honda which we regarded as underpowered for coastal cruising. We sold the Honda and fitted a new 80 hp Yamaha four stroke.
We have found that prop size makes a significant difference to performance and economy. The eventual choice for us was 13 1/2 " diameter x 15 " pitch.
Whether or not a 60 hp engine will suffice will depend on your use of the boat. In rough western waters we find the larger engine very useful. (I realise that Orkney state the hull is linited to a 75 hp outboard but Yamaha don't do one. We looked carefully at the alternatives and concluded Yamaha made the best engine for us.)
In flat water we can get up to 26 kts at 5500rpm, but that's noisy and boring. We usually travel at 12 - 15 kts in reasonable water or 18 - 20 kts if there is a reason to hurry. Alternatively, if it's very rough, the boat is excellent at 6 - 8 kts.
We also have hydraulic trim tabs. They are quite useful in the 9 - 15 kts range, but very unhelpful at higher speeds - one can dig in suddenly, causing the boat to list alarmingly.
I hope this helps.
Whitelighter
Well-Known Member
Suggest immediat purchase of all 6 Howards Way DVD's and a week or so's quiet contemplation of 1980's Southampton...
halcyon
Well-Known Member
Is it the same one that Jack built? that was a displacement fishing boat.
Brian
Brian
N
NJMcK
Guest
[ QUOTE ]
Suggest immediat purchase of all 6 Howards Way DVD's and a week or so's quiet contemplation of 1980's Southampton...
[/ QUOTE ]
See this .
Suggest immediat purchase of all 6 Howards Way DVD's and a week or so's quiet contemplation of 1980's Southampton...
[/ QUOTE ]
See this .
Whitelighter
Well-Known Member
oops /forums/images/graemlins/blush.gif
Do you get that alot then? /forums/images/graemlins/laugh.gif
Do you get that alot then? /forums/images/graemlins/laugh.gif
