Few questions.Rib project

[Starovich]

I'm not sure what you are expecting to see, the vast majority of ribs are bespoke. not like cars where many look the same.

Its an older cobra,there are many on the web, many owners on the forum. They are more on the leisure side of the market now (look at the website). You are quite correct none will look like yours, that doesn't make it special, just built to a spec set out at the time.

Twins/righting frame are a giveaway that its was a commercial spec boat, many commercial operators want redundancy of twins, (search this forum for pros and cons of twins).

As mentioned if you want 100% accurate definitive answers of the initial build go to the horses mouth (RNLI/Cobra).

As to repowering there are guys who have done this on the forums, take look at the built threads, some converting from twin to single, inboard to outboard or viceversa.

[ShinyShoe]

Originally Posted by abyss

Had no intension to offend anyone by having my doubts , but the often answers like :I don't think so or in my opinion - are wrong.

Because someone may come along and prove them wrong. But I'm 99% certain they wont. Its a common ebay listing thing to see "Ex-RNLI" on some scuzzy RIB that happens to vaguely look like it was once a RNLI RHIB to the uninitiated.

The RNLI pedigree is good.

Originally Posted by abyss

If someone would answer : no, not RNLI because this and that etc... Then I wouldn't question that any more

Fine - No :-P

Originally Posted by abyss

I not hoping that's ex rnli. Way should I ?it is what it is and if it floats that's good enough for me. Definitive answer would help me search for the answers of the other questions that I might have .

So move on to the other questions ;-)
If it doesn't matter if its RNLI and you are being told its almost certainly not then move along and start with questions we can answer...

To be clear the RNLI boats were not Cobras. So we are probably all in agreement it was not an RNLI rescue boat. Occassionally a weird situation comes up where the RNLI take over an independant station and so technically may have used their rescue boat for a short time and most of the independents will be a typical commercial RIB. But the pedigree is then not really an RNLI RIB.

The other rare situation would be when the RNLI have a support craft, not used for rescue work but used as a work boat, crew transfer boat for a moored lifeboat. Some of those may be commercial craft rather than from the rescue designs. But it still wouldn't quite be the full RNLI pedigree although may well be better maintained than your average dive club RIB!

Originally Posted by abyss

About the hull... Never saw before that leisure craft would have that kind of A frame with capsize recovery device and radar reflector...also the gel coat color,twin underfloor petrol tanks...
Anyone with more knowledge about RNLI boats?

Originally Posted by abyss

Cause believe it or not I'm never saw another picture of the boat on the web that looks like mine.

Originally Posted by Starovich

30 sec on google

Originally Posted by abyss

30 sec on google show that what I have seen for months.
No of them look one to one like mine.

I may be wrong, but I think Starovich was directing you to a number of examples of non-RNLI craft with re-righting frames.

What makes you think this boat was an RNLI craft

[Nos4r2]

Originally Posted by abyss

Ok then, how about laser cut, inch thick ,steel plate to mount engine lower then transom top and use existing holes of the two outboards to secure it?
I'm gonna look for twin setup for sale but up to then this mariner has to be ok.

It'd be easier to sell the lot and buy something that works together.

That old 135 is a lemon. If you drop it below the level of the transom, you'll have to step it back enough to get the steering to fit. You're unlikely to be able to rig it properly if it's dropped 7 inches -the rigging tube will be right against the transom and will bend the control cables very sharply if you tilt it. Essentially, it won't be ok.

. The hull, while nice is probably a bit higher spec than you need and looks like it probably needs a full re-rig.


I refitted a 7.8m rib a couple of years ago, and it cost an insane amount of money. I had everything there, fitted and at least semi-working to start with before I dismantled it. You don't have that luxury.
As it's your 1st boating experience you'll find that boat is a money pit the likes of which you've probably never seen. It'll be a cracking boat when it's done properly, but bodging on an underpowered ancient gas guzzler is just going to make the whole thing an even bigger lemon.

Given that it appears to have a bottle rack fitted as well as a self-righting A-frame, I reckon it's a pretty good bet it was a commercial dive boat originally.

[abyss]

Gents,
making no waves here...the discussion is the mother of truth....
i didn't bought it as ex rnli rib so no real reason of wanting it to be one,but i was speaking with with indespension trailer sales guy when i was getting new axle beams etc. and he asked the trailer chassis nr. so after i was asked im i rnli representative cause the trailer was delivered to them originally.
i know trailer is not the boat ,but including boat similarity's ex rnli rib fits the picture.only thing which confused me was the cobra sign on the tube which wont be on any life rescue craft.
IMO the boat was re-rigged several time before me and single console and rack which looks like dive bottle rack was fitted at last. just putted them in the boat after i dismantled it ,to plan new layout.
when i got the boat it was semi working too.i got all the gauges,wiring ,fuse block ,compass,battery switches ,hydraulic steering,chart plotter etc.
no engines only...
so when im saying i need it for this season i mean just hook up the engine correctly and give it a go...then see what is good or bad.
i agree that is easier to sell the one and buy two new,but easier is not cheaper and at the moment i don't want to spend more then i have too.
any info on improvement of the engine reliability (like the oil mix mentioned before )would be greatly appreciated .
i will stick few more pictures of the rig,plan and some of progress when will have any.
regards and thanks.

[Bigtalljv]

I have a 7m zodiac which looks to be a bit heavier than your hull and I can't imagine a 135 doing much of anything for it. I run a single 250 happily.

What are the merits a good cobra hull, color aside? If yours is a good hull then look for a proper engine. Either the right size single or twins. There seem to be more used motor options over there and it sounds like you cant do much worse than that old mariner. Shortcuts in boating can make the experience unpleasant and possibly dangerous.

I refit my boat to save money. It would have been cheaper to buy the one I didn't think I could afford. But I have a great boat refit with my own hands that is like no other

Jason

[Mollers]

Originally Posted by Nos4r2

It'd be easier to sell the lot and buy something that works together.

Sound advice.

[Nos4r2]

I reiterate what I said below. Your main cable inlet on that motor is going to be below the top of the transom if you sit that motor on there. It's going to damage the control cables if you tilt the motor.

Originally Posted by Nos4r2

That old 135 is a lemon. If you drop it below the level of the transom, you'll have to step it back enough to get the steering to fit. You're unlikely to be able to rig it properly if it's dropped 7 inches -the rigging tube will be right against the transom and will bend the control cables very sharply if you tilt it. Essentially, it won't be ok.

Originally Posted by abyss

easier is not cheaper

In your case it is-your suggested cheaper option isn't a feasable option.

To give you a comparison, if you bought a 38 tonne Scania tractor unit with no engine, you wouldn't even bother trying to put a 1980s V8 Range Rover lump in it. This is essentially what you're suggesting.


Ref RNLI, the RNLI generally only use Atlantics-which are of a similar size. That's probably why your trailer comes up as ex RNLI.

[Last Tango]

I'll await the onslaught for this sacrilege......but if your absolutely bl**dy determined to stick with the boat then:

1 If you lop 7" of the transom you have a boat that you'll struggle to give away when the time comes.
2 It has no well so you'll constantly be getting water over the transom.
3 It's not likely to plane loaded up with 6 divers plus gear.

So that engine has to go.

From the proceeds you might pick up a couple of 40hp LSs.

It will definitely not plane but it should get you there and back at around 10knts at about 2mpg.

Problems 1 & 2 resolved and the lot could be re-sold as three separate components.

This is far from an ideal solution but is probably as close to a "no-cost" option as you're going to get..

[abyss]

I call cobra ribs today...they never did any ribs for rnli.that question is answered.

[beamishken]

Why not just make up a fairly basic stand off bracket that picks up on the existing holes to avoid having to butcher the transom & give it a try
You've little to lose apart from a bit of time
It may be a disaster & you find the engine is underwater before the boats off the trailer or you could surprise everyone & find its slow but livable with
Not the 100%answer but might get you on the water sooner & not butchering the boat into the bargain

[abyss]

And That's what I gonna do. Until I make a my mind about do I sell my engine and look for twins or buy another one like I have.
I'm not cutting my boat .that tought is history.
Have no problems making a bracket and I'm sure he will be ok to hold the engine. Few things needs to be engineered before: make something that I won't bend control cables when tilting. And find out underfloor petrol tank locations.

[Ribochet]

Originally Posted by abyss

I call cobra ribs today...they never did any ribs for rnli.that question is answered.

And there was me thinking that the question HAD been answered

Originally Posted by Starovich

I would say, not RNLI.

Originally Posted by Mollers

The rig is commercial, but not ex-RNLI.

Originally Posted by Ribochet

Yes and it is definitely not ex RNLI

Originally Posted by willk

this isn't an RNLI boat either.

Originally Posted by ShinyShoe

To be clear the RNLI boats were not Cobras.

[Mollers]

Originally Posted by Ribochet

And there was me thinking that the question HAD been answered

The fella just had to make sure.

[beamishken]

Come on guys cut the guy some slack he's new & doesn't know the level of knowledge on here
It's all to easy to be negative about what people are trying to achieve
not everyone has deep pockets or years of experience

[9D280]

Abyss.

Theory is all well & good, but some of us have a budget and a hull.

Your current combo is probably not too dissimilar to a scaled up version of my first RIB- an SR4 with a 25 Hp on the transom. Read the forum here you'd think I'd have struggled to get out the marina! needless to say I had some amazing cruises with that boat.

Your hull is definitely set up for twins, and I would guess that two of your current engine would do nicely (check the maker's plate / book of words for actual HP ratings!)

Now, assuming you have that engine already or it's a nice easy / cheap buy, as I said before, the big issue might be finding a twin for it, BUT old engines appear all the time, and I would be reasonably confident you could find it a twin at a sensible price.

Now, above there are many posts about "buy a new <whatever>, but I will throw this into the mix: I bought my 1973 vintage 60Hp clamshell for £200 with no guarantees (and the fallout from that decision is contained in many an old post on here!). A used modern 4-stroke 60Hp would have set me back the best part of £8K. Now, I agree the modern engines are probably slightly more fuel efficient (definitely quieter!), but how long will it take me to burn enough fuel to equal a £7800 purchase saving? (OK, it's more of a £6000 saving by the time I fully rebuilt it, but the point still stands!)

Me? I would Google / Ebay / whatever you local boat auction is for that style / HP of engine (remembering it's a rebadged Merc) and see what a twin would cost you. My gut feel is that would be a long term easier way to go based on sawing transoms about & the "lardy diver kitting up" comment above...

Also do a search for twin single - if you want backup a "big aux" isn't such a bad thing!

[abyss]

Someone really likes to say:- I told you so ok . I say it : all of you were right . I was wrong !
If that's good enough I want to move on to second part.

[abyss]

which is:
i understand that engine i have is old, inefficient ,loud and stinky...but, even if i will find some twins for sale (in my price range) they will be very close to the era where this mariner is from. so that said -is it better ,easier look for twins or look for another 135 mercury/mariner?
in fact ,non of the things (loud stinky etc..) bothers me .cause:all i need the rib for- is diving.
and that how it works: i load everything and go about 30 min. MAX to the dive site.stop .dive once,then once more and go back .another 30 min. multiply that about 20 times per season...

[abyss]

[QUOTE=9D280;674266]Abyss.

Theory is all well & good, but some of us have a budget and a hull.


Now, assuming you have that engine already or it's a nice easy / cheap buy, as I said before, the big issue might be finding a twin for it, BUT old engines appear all the time, and I would be reasonably confident you could find it a twin at a sensible price.

Now, above there are many posts about "buy a new <whatever>, but I will throw this into the mix: I bought my 1973 vintage 60Hp clamshell for £200 with no guarantees (and the fallout from that decision is contained in many an old post on here!). A used modern 4-stroke 60Hp would have set me back the best part of £8K. Now, I agree the modern engines are probably slightly more fuel efficient (definitely quieter!), but how long will it take me to burn enough fuel to equal a £7800 purchase saving? (OK, it's more of a £6000 saving by the time I fully rebuilt it, but the point still stands!)

Me? I would Google / Ebay / whatever you local boat auction is for that style / HP of engine (remembering it's a rebadged Merc) and see what a twin would cost you. My gut feel is that would be a long term easier way to go based on sawing transoms about & the "lardy diver kitting up" comment above...

exactly my point... and thats what came up like someone said after 30 sec of google...

Mariner 135Hp Outboard | eBay

price is bit high sided, but they come up frequently

[Nos4r2]

If you can get a second 135 Merc/mariner the same, go for it. With 2x135hp, you've got a manageable boat which at a guess will burn less fuel than with the single 135 -ie, it'll have an actual planing cruise speed rather than flat out and falling off the plane with a load on.

FWIW though, if you're going to do it, do it 1st or you're going to have to buy new cables for the motors and re-rig them.That's a serious pain in the butt. Push-pull cables aren't easy to do away with excess lengths, specially if you've got under deck trunking.

[A1an]

I feel your pain, boating on a budget is a real struggle, especially when you have the size of hull you have.

IMHO?, a pair of those 130's are going to be shockingly pricey to run/maintain. I ran a pair of 60s on a 5.8m hull and fully loaded i was using anything up to 1.4 litres a mile. I couldn't stomach it.

I bought a four stroke and notched the transom to accept the single. Many people frown upon it, as long as its done properly I don't fully understand why. I've saved 40kgs on my transom so in theory it should sit a little higher in the water and the cut out takes the transom height to a normal long shaft transom anyway.

I've gone from 2 older/thirsty/pricey/inefficient 2 strokes to a modern/economical/lighter/more reliable 4 stroke. It's a win win situation in my eyes.

I don't have pocketfuls of cash I can chuck at a boat and couldn't be doing with the hassle of buying and selling. You can only piss with the cock you've got.

Basically what I'm trying to say is.....I'd cut the transom and go with a bigger single because I don't have the pockets but that's just me.