Turning a hard boat into a rib?

Cagedbanana · 30 January 2011, 14:41

I just wanted to know if it could be done and if so what would be involved? I got as far as removing the top deck, but wanted to know if a new transom would have to be built to except the tubes an also how much, roughly tubes are, I'm sure they vary but just wanted to see again if this could be a viable option
thanks
chris

chewy · 30 January 2011, 14:44

It can be done and for cost of tubes it depends on the length of your boat and what you want fitting?

Vandad · 30 January 2011, 14:47

Quote:

Originally Posted by Cagedbanana

I just wanted to know if it could be done and if so what would be involved? I got as far as removing the top deck, but wanted to know if a new transom would have to be built to except the tubes an also how much, roughly tubes are, I'm sure they vary but just wanted to see again if this could be a viable option
thanks
chris

Don't bother. we did once and the result was just waste of time. It is mainly because the rib does have a V shape hull as it will be supported by air chambers. But the normal boat can't have as it won't float then!

We converted an aluminium boat and had a 2nd hand old inflatable and thought we can use the air tubes....

chewy · 30 January 2011, 14:50

Quote:

Originally Posted by Vandad

Don't bother. we did once and the result was just waste of time. It is mainly because the rib does have a V shape hull as it will be supported by air chambers. But the normal boat can't have as it won't float then!

Explain the above?

Alot of RIBs are based on speed boat hulls.
If you choose the right hull and do the job correctly it won't be a waste of time.

Screaming04 · 30 January 2011, 15:07

Quote:

Originally Posted by chewy

Explain the above?

A lot of RIBs are based on speed boat hulls.
If you choose the right hull and do the job correctly it won't be a waste of time.

Rib hulls are steep and narrow... my 24 footer's grp beam is just over 5 feet, keeping the overall beam to 9 feet with the tubes. Do you now of any 24 foot long 5 foot beam hard boats? Didn't think so, they don't exist... even if you cut the hard boat down to the waterline, it's still too beamy (the rigid part) and will not perform like a rib.

chewy · 30 January 2011, 15:20

Quote:

Originally Posted by Screaming04

Rib hulls are steep and narrow... my 24 footer's grp beam is just over 5 feet, keeping the overall beam to 9 feet with the tubes. Do you now of any 24 foot long 5 foot beam hard boats? Didn't think so, they don't exist... even if you cut the hard boat down to the waterline, it's still too beamy (the rigid part) and will not perform like a rib.

So no speed boat hulls have ever been converted to RIB's then?

Screaming04 · 30 January 2011, 15:23

Quote:

Originally Posted by chewy

So no speed boat hulls have ever been converted to RIB's then?

Perhaps they have, but not by simply hacking up an old speed boat hull. They may use the v hull form of a speed boat hull but modify the mould to a narrow beam.

chewy · 30 January 2011, 15:30

Quote:

Originally Posted by Screaming04

Perhaps they have, but not by simply hacking up an old speed boat hull. They may use the v hull form of a speed boat hull but modify the mould to a narrow beam.

Sonar on here used a Fletcher GTO although never got it finished the proportions looked ok.
Odds are he won't do it as he's still at school anyway!

Dirk Diggler · 30 January 2011, 15:49

Quote:

Originally Posted by Screaming04

Rib hulls are steep and narrow... my 24 footer's grp beam is just over 5 feet, keeping the overall beam to 9 feet with the tubes. Do you now of any 24 foot long 5 foot beam hard boats? Didn't think so, they don't exist... even if you cut the hard boat down to the waterline, it's still too beamy (the rigid part) and will not perform like a rib.

I certainly know of several that would fit the bill, over here in the UK, a 5ft CHINE beam is pretty common for a 24ft boat, you seem to forget that topsides tend to flare out, and so a 5' chine becomes 6 plus feet at the rubrail.

Screaming04 · 30 January 2011, 16:18

Quote:

Originally Posted by Dirk Diggler

I certainly know of several that would fit the bill, over here in the UK, a 5ft CHINE beam is pretty common for a 24ft boat, you seem to forget that topsides tend to flare out, and so a 5' chine becomes 6 plus feet at the rubrail.

I'm aware of the flare but again 24 foot length and 6 foot beam?! You must have some weird tippy boats over there! Standard beam on a hard 24 footer would be 8-9 feet. 18 footers are 7'6". Hard boats, even with a decent deadrise have fairly wide flat sections (or reverse chines) outside of the V for stability...they are not seen on RIB except perhaps in a "med style" hull... which we all agree on this site, is not what most of us like in a rib design.

Show me a pic of a hard boat that has successfully been modified with toobs attached and make me a believer. Otherwise I stand by Vandad's experience and my opinion that it would be a huge waste of time/money/effort to attempt a conversion.

Hightower · 30 January 2011, 16:31

Quote:

Originally Posted by Screaming04

I'm aware of the flare but again 24 foot length and 6 foot beam?! You must have some weird tippy boats over there! Standard beam on a hard 24 footer would be 8-9 feet. 18 footers are 7'6".

The reason that rib's perform so much better in rough water is because of their ability to be built with a narrow, rigid V... the tubes provide the floatation required to make up for the narrow beam at rest... (I'm aware that some tubes, like mine, stand clear at rest...but they're in the water as soon as a roll starts)

Show me a pic of a hard boat that has successfully been modified with toobs attached and make me a believer. Otherwise I stand by Vandad's experience and my opinion that it would be a huge waste of time/money/effort to attempt a conversion.

But you also have to remember that the mounting point for tubes is roughly in the centre and that the beam measurement for RIBs is between the tubes. This will explain the narrower RIB measurement relative to a hard boat.

Screaming04 · 30 January 2011, 16:36

I've been adding to my last post...

Hard boats, even with a decent deadrise have fairly wide flat sections (or reverse chines) outside of the V for stability...they are not seen on RIBs except perhaps in a "med style" hull... which we all agree on this site, is not what most of us like in a rib design.

You certainly could bolt tubes onto a rigid boat, in my opinion, you would have just that... a hard boat with tubes. Not a rib.

chewy · 30 January 2011, 17:20

Quote:

Originally Posted by Screaming04

You certainly could bolt tubes onto a rigid boat, in my opinion, you would have just that... a hard boat with tubes. Not a rib.

So a what point would a hard boat with tubes become a RIB?

Ring seem to be doing ok....

willk · 30 January 2011, 17:51

Oh man, when Cookee sees this, they're gonna havta shoot him in the ass with a tranquiliser dart. He was so looking forward to a tubed version of his new handcrafted hardboat.

He might still be OK though, it did look a bit "tippy"

Screaming04 · 30 January 2011, 17:52

Quote:

Originally Posted by chewy

So a what point would a hard boat with tubes become a RIB?

Let me reverse that for you... is a hard boat with a bicycle tube attached a RIB?

Are you really this thick or just messing with me?

chewy · 30 January 2011, 18:01

Quote:

Originally Posted by Screaming04

Let me reverse that for you... is a hard boat with a bicycle tube attached a RIB?

Are you really this thick or just messing with me?

How dare you!

It was a simple enough question which stemmed from you saying bolting tubes to a hard boat doesn't make a RIB.
So seen as you must know what is and what isn't a RIB can you define the cut off.... or are you really this thick?

Which of these is and isn't a RIB then and why, post 135:

http://rib.net/forum/showthread.php?t=33407&page=14

Downhilldai · 30 January 2011, 18:07

Where's Leeway when you need him?

willk · 30 January 2011, 18:10

Quote:

Originally Posted by Downhilldai

Where's Leeway when you need him?

We need someone to DEFINE the cut off, not actually let rip with an angle grinder

wiLlfish · 30 January 2011, 18:13

Quote:

Originally Posted by Screaming04

Are you really this thick or just messing with me?

yawksher nobburs downt messs

chewy · 30 January 2011, 18:14

Quote:

Originally Posted by willk

We need someone to DEFINE the cut off, not actually let rip with an angle grinder