Single outdrive, any differences from single o/b? Advice

[Tideway]

Originally Posted by Keith Hart

"We often set nets (bow on) from the foreshore and these require a fine degree of control with the engine generally trimmed up quite high (just below the surface and pulling) running astern so that we can pull the boat and the net away from, the shore"

I think that this guy is a salmon poacher...

Keith Hart

This amused me! Quite the opposite in fact, poachers & illegal netsmen will not be v.pleased to see us. Vessel will be used in fisheries enforcement and survey (hence the nets) roles. t

[Bajan]

That is quite amusing.

[tim griffin]

coming back on to the topic
have you given any thoughts to jet drive as you are working in estuaries
so no probs of grounding , and i take it you shoot the nets and recover from the bow, loads of guys on here that can give you advice on this set up

SIMMONSO what are you on about, never been shown steer then gear
come on mate this is basic level 2 stuff my last rib was a 9 metre with 265
tdi to an outdrive and it was the sweetest thing to drive .
regards tim
www.griffmarineservices.co.uk

[simmons0]

Have had bad experience of big prop 21" with 115hp Mercury at idle speed once! Supplier knew nothing, we ended up on 17"!

I said it would be similar to that Tim, seen as he will be running a 21" or bigger on the new boat...

[tim griffin]

on my 6.9 rib 150 hp opti and 21 prop no problems for my students turning in confined spaces and even having a awkward marina berth
the boat is always under total control by the student , no surging ahead
and embarasing moments as they know how important neutral is and steer then gear in close quarters manouvering,
regards tim
www.griffmarinesercices.co.uk

[Tideway]

Originally Posted by tim griffin

coming back on to the topic
have you given any thoughts to jet drive as you are working in estuaries
so no probs of grounding , and i take it you shoot the nets and recover from the bow, loads of guys on here that can give you advice on this set up

SIMMONSO what are you on about, never been shown steer then gear
come on mate this is basic level 2 stuff my last rib was a 9 metre with 265
tdi to an outdrive and it was the sweetest thing to drive .
regards tim
www.griffmarineservices.co.uk

Tim,

Yup we had considered jet(s), but we had a very strict length (<6m) and weight (<2tonnes) requirement for the boat to fit existing equipment, this has led to a small boat that has to do great variety of jobs. Jets are great for close in work, but for our applications we can get in/out ok with props and if necessary a bit of muscle power! The estuary has a great deal of plastics/rubbish & general detritus, so jets can be a mixed blessing. Props are vulnerable, but can nearly always be freed/replaced in the field. Jets mean that if you can't clear em by backflushing, then you need to get right into the gubbins or under the boat . Plus we would lose horsepower and top end, which would mean with the distances covered in a working day it would be too time consuming to reach the edges of the area (approx 100mile of river/estuary) do the job and return. Thanks for the v.sensible suggestion, it is the obvious way to go if you don't have the criteria that we are working to (which I hadn't posted!).

For info: The 21" prop was fitted to a Mercury Optimax 2 strk115hp o/b when supplied to us, the reasoning was that it would aid us carrying heavy loads. It meant an alarming speed forward in tickover and absolutely no chance of attaining the higher end of the rev range, even when light! Switch back to a 17" from our old engine and all was ok again. Selecting props seems to akin to witchcraft, so never mind....

thanks all for the info, it is v interesting.

t

[tim griffin]

ahhh
now i see, if it was me i would go for the outboard, just because of the weed
and rubbish,(think the RNLI could tell you about jets on the Thames) also easier to beach do like outdrives but not sure if would be
the best for your application, can you claim the duty back on the fuel
i assume as fisheries protection you can , so running cost's reduced,keep us posted with the final outcome .
regards tim
www.griffmarineservices.co.uk

[Tideway]

Tim,

We've gone for the outdrive (boat is being built!), reason being is that we used to use either twin 50s or single 115 2strks (all but one were Yams). These were great, v.v.v.reliable but JUICY. By switching from fibreglass to aluminium, the weight saving has been enough for us to get away with a diesel. This wasn't something we had considered, but as this was the first chance that we could get away with handling petrol (x2 100ltr tanks on old boats) we took it, we decided it would be much safer, cheaper to the taxpayer (no duty) and more available on the river. The diesel option was suggested by manufacturer, we had been looking at 4 strks. Hopefully, in the long run she'll pay for the diesel option with the fuel savings. We are normally on about 280-300 hrs a year.

Looking forward to getting a purpose built boat rather than making do, but she ain't gonna be v.pretty!

regards,

t

PS. i do like jets though, if I could afford a boat they would be on it.

[Tideway]

And here she is:

http://www.allyduck.co.uk/aluminium-...ch-vessel.html

As some of the other members on the forum have commented in a thread started by Manos, they ain't pretty!

BUT she'll take a pounding from day one and hopefully pay back the expense of a diesel from the fuel savings. Sea trials are next Tuesday and she'll be in the tideway by the end of August, if everything goes ok.

Advantage of ali over GRP is that you can cut and weld it into any shape you want, so no problem with one off mouldings etc....The manufacturer has been extremely helpful and made many sensible suggestions and refinements to what was a rather unusual specification.

Our old Tornado 5.5 can now honourably retire.......

Thanks for all the advice and tips. They are much appreciated,

cheers,

t

[jwalker]

Folk often don't complete threads, it's nice to see the outcome.

[Nick Hearne]

Looks fit for the job, but will knot win marks for style!
Nick

[Tideway]

Nope you are right, even with the beer goggles, she isn't a looker . But, she'll do the job.....safely & properly. I wish we weren't sensible, I did like the Tornado and Dory, they really shifted. Ho hummm.

t