Opti Powered 5.4 - Page 2

dctucker · 05 November 2006, 18:52

Quote:

Originally Posted by Turbodiesel

Well, i work for Barrus (Mariner/Mercury UK). Im lucky enough have a job thats also my hobby!.
I do all the commercial trials for outboards and the pre production work on new bulids and refits etc. Its the MoD that are buying the engines luckliy not me!!!

Thats why there all Mariners and no other makes. MoD only use Mariner and Mercury.

Okay, I get it. Wish I were so lucky!

Isn't the 90 Opti a tad portly for the transom of a 5.4 SR? As I recall it was dramatically over the specified max weight for the transom. It's also outrageously LARGE for its output.

ian parkes · 05 November 2006, 19:19

Would have thought the MOD would have progressed to 4 strokes by now

Turbodiesel · 05 November 2006, 19:41

Quote:

Originally Posted by dctucker

Okay, I get it. Wish I were so lucky!

Isn't the 90 Opti a tad portly for the transom of a 5.4 SR? As I recall it was dramatically over the specified max weight for the transom. It's also outrageously LARGE for its output.

Well, Avon tell us it will be fine, they have done some clever calculations and have worked out the weight will be ok. The 3 cylinder Opti's (75/90/115hp) are all the same weight so if the 75 is ok then the rest will be fine. But we are taking carfull measurments of how much free board there is on the transom!!

Biggles · 05 November 2006, 20:33

Quote:

Originally Posted by ian parkes

Would have thought the MOD would have progressed to 4 strokes by now

Not the last time I used their 5.4s. But they have progressed to a much more sophisticated 5.4. Orange in colour with much better seating and storage etc.

If it was marketed on the civilian market at a decent price it would be a world beater.

Turbodiesel · 06 November 2006, 10:15

[QUOTE=ian parkes;172818] Would have thought the MOD would have progressed to 4 strokes by now

[/QU

They are not interested in four storkes, to heavy for most of the small boats, and more things to go wrong.

dctucker · 06 November 2006, 12:42

Quote:

Originally Posted by Biggles

Not the last time I used their 5.4s. But they have progressed to a much more sophisticated 5.4. Orange in colour with much better seating and storage etc.

If it was marketed on the civilian market at a decent price it would be a world beater.

PICTURES!

Biggles · 06 November 2006, 12:46

Quote:

Originally Posted by dctucker

PICTURES!

Sorry I haven't any pictures but I will try over the next few months. Don't know if taking pictures of MOD RIBs is against the Official Secrets Act so I'll have to be carefull.

dctucker · 06 November 2006, 14:53

Quote:

Originally Posted by Biggles

Sorry I haven't any pictures but I will try over the next few months. Don't know if taking pictures of MOD RIBs is against the Official Secrets Act so I'll have to be carefull.

Probably not worth getting thrown in the Tower of London for, but I'm sure I'm not the only one who wants a look!

ian parkes · 06 November 2006, 19:22

If the ancient things the Plymouth Mod Plod were using during Navy Days to spoil our weekend were anything to go by then an autolube 2 stroke will be a novelty
This http://cgi.ebay.co.uk/Inflatable-60-...c mdZViewItem was about the standard , but more patches .

But then again such Rude miserable bastids as those prticular Mod Plod don't deserve anything better .

Nos4r2 · 05 January 2009, 16:22

Out of interest (old thread I know!) what were the results like with optis and did you get to try a 115 in the end?

Turbodiesel · 10 January 2009, 20:24

This was a long time ago!. i cant remember, but i will have a look in the file at work and let you know next week!

Turbodiesel · 16 January 2009, 10:20

Ok, a brief trail report for you....

5.4m Searider with Mariner 75hp 2 stroke
Max Rpm: 5600
Max Speed:35.9knts
Load 2 people plus 50ltr fuel
Prop: 18" Vengeance

5.4m Searider with Mariner 90hp 2 Stroke
Max RPM: 5400
Max Speed: 38.2knts
Load: 2 people plus 50ltr of fuel
Prop: 20" Laser 2

5.4m Searider With Mariner 75hp Optimax
Max RPM: 5500
Max Speed: 33.7
Load: 2 Plus 50ltr fuel
Prop: 18" Vengeance

75hp Optimax lifted up one hole on Transom
Max RPM: 5600
Max Speed: 34.7knts
Load 2 Plus 50ltrs fuel.
Prop: 18" Vengeance

We did try a huge amount of different props but these are the best results out of each prop trial. We never tried the 115 Opti as it was not needed. Annoyingly i cant find the 90opti results!. We also tested engine with various weights from 200kg upto 600kg.
Also worth a note the Dyno results for the above engines.

Mariner 75hp 2 stroke Dyno run @ 81.2hp
Mariner 90hp 2 stroke Dyno run @ 94.2hp
Mariner 75hp Optimax Dyno run @ 74.8hp
Mariner 90hp Optimax Dyno run @ 90.0hp

We also found that every boat is different!, and some are faster than others. We had a 5.4 Searider here a while ago with a 90hp 2 stroke on that on a good day would top 40knts.

ollyit · 16 January 2009, 11:57

Interesting reading mate, thanks

Nos4r2 · 17 January 2009, 00:38

Yes,very much appreciated

Very interesting that the old tech Mariners were making more than stated HP.
Looks like I'm bang on with my setup then:

Navy Sr5.4 with 85hp Yamaha 2 stroke-raised one hole
Max RPM 5300
Max speed 38.2 knots
Load-1 fat git (probably close to 1 3/4 people),100 litres fuel and 50kg+ of gear
19" Michigan Wheel Match prop

matt h · 17 January 2009, 07:44

Turbodiesel, thanks for the info, if i can top 40 kts with mine then its bang on, cant wait to try it out,

JSP · 17 January 2009, 08:29

That's very interesting TB.
Have been told by someone who owned my SR (couple of owners back who shall remain nameless unless he comes forward. Clue: sounds like Mavid Danning

) that they got 40+ knots out of her. But at 18stone with one ginger leg and curly teeth I'll be lucky to empty the hull

That speed was with the hull blocked off if that makes any difference.