New Rib project

Hi Folks,

I've been researching a project for a few weeks now, and I can find lots of non specific discussion but I cannot find any actual builds or logs.

I've bought 2 rib hulls a 5m (tubeless with centerconsole) and 4m (tubes beyond repair and center console).

Firstly I intend to fiberglass some d-tubes to the 5m for ease of diving, stability and storage at the rear. Then forward I would like to see the tubes change to more traditional fishing boat raised gunnells. 4m project will depend on the success of the 5m project.

The rib hulls at present have the small flange that the rib tubes would normally sit on.

I'm spending a few months researching this so I'm not looking for any fast answers, but I am comsidereing the best way to attach the fiberglass tubes.

Should I use the existing flange and sit them on this or scarf them to this? Or should I cut off the flange and scarf them to the collar?

Either way I think I am going to have a near 90' angle from the existing hull and the new tubes and I'm concerned about the force acting on this as it slams into an oncoming wave at speed. I think a 90' hard chine would be ok as its integral to the boat but I'm not sure about these tubes?

I was thinking of using a closed cell foam rib in a "P" shape and glassing this all the way down to the underdeck ribs and up to the fiberglass tubes to reinforce it. But this would make the boat very heavy.

I have searched on these forums (and other forums and the web) for Rib, RHIB, RTB and RBB and have found lots of discussion but nothing concrete. I'd love to see a step by step of someone who has done this before? If there is none maybe I can show mine?

I like the look of http://www.poolesportsboats.com/endeavour-540rtb.html but I think the full tube takes up too much space and a D tube would be a better option. I'd also like higher gunnels at the front and maybe even a cuddy! Maybe a cross between a the above rbb and my orkney 590 fishing boat?

I love to hear you thoughts espcially regarding strenghting and supporting the D tube to the hull.

Edit: Bolger Micro trawler is interesting for its 90' angles, but as its origionally made from wood I think it would have better strenght (and heavier weight) than a pure fiberglass angle?

E.g. this in only fiberglass

from http://www.duckworksmagazine.com/00/DM1999/articles/microtrawler/index.htm

 

Check this Brazilian boat

 

Thanks edmundo, that is a very nice design, is it yours?
I've seen your infusion links and they are very good.

I see that your foam (?) collars in your picture do not protrude very far? I would expect a fiberglass tube to have a radius of 400-500mm so I think more force will act on it as it comes in contact with a greater amount of water.

That said... the overall design of the boat with lower stern and raised gunnel's forward is what I am looking for! Do you find the raised gunnel's keep the deck much dryer?

 

The collars have a fiberglass shape covered with an EVA foam sheet. It´s covered again with a PVC fabric. The collar works like a fender and keep the bow out of water specially "downwind". But it keep the deck very very dry.
The stern is lower, because I´d design this boat to follow my sun in Laser regattas and for spearfishing( it´s lower to jump in the water). It´s very stable and don´t deflate!!! like a RIB. It´s all infused and light 26 foot>>500kgs. Do you need any help??

 

Wow, that sounds great!
I have a 6m fishing boat but its nearly impossible to climb back in when diving. I want fiberglass tubes as I freedive and spearfish also I can only imagine Brazil waters are amazing to spear in!

I do indeed need help. I am a usability professional/researcher and want to design a very small light practical boat for freediving/spearfishing. I can do fiberglass repairs but I have no experience in design. e.g. to repair something I can see how it is made and copy it in the repair. But to design a boat... well I am hoping to see how others have done so already, and try to learn from them.

I have bought 2 hulls a 5m rib hull and a 4m hull. There are old tubes on the 4m and I may fill them with small balls at a later date once I finish the 5m project.





You can see our lovely weather

I am trying to plan as much as I can now and hopefully I might start this project in the new year and have a boat ready for our season start next may.

Here is a picture of the rib hull I have.

 

I think the easier way to make fiberglass tubes to this hull would be using a 400mm PVCpipe as the shape an fiberglass over. You can also use EVA foam over it(using contact glue)and cover everything with PVCfabric.
PS:I´m sure spearfishing in Rio is easer than in Ireland cold water!!!

 

Is ok in Ireland, we just use very think suits 

Anyway as its a relatively small boat I want “D” shape tubes instead of “O” shape.
I think this will still give the stability benefits of a rib but also give extra deckpase or storage space.
To do this I do indeed plan to use 400mm approx pipes if I can find them locally.
I was planning to cut the pipe in have and use it as a mould.
I will need to extend the transom so that it will meet this “D” tube... or maybe put in a brand new transom??

From here it gets tricky as I am unsure what the best way to attach this tube to the existing structure.

There is already a flange visible in the photo that the original tubes sat on. I was hoping to fit the PVC tube mould so that it sits under this flange.

I was then going to give 2 layers of gel directly into the tube mould with a sandwich of several layers of CSM, roving and CSM.
I would glass the inside of the tube completely and reinforce the joint with the woven.
I would reinforce this with “P” shaped ribs which spread the load from the tube to the existing hull.

Honestly its all in my head at the moment and the design I have is varying based on difficulty and trying to understand what kind of strength and support is needed where the Flange meets the new fibreglass tube.

Have you any idea of the strength of fibreglass I need to make sure the tube doesn’t come off in really rough waves?

Thanks!

 

The most important is to prepare very well the surfaces where will be the secondary bonding.(sand and clean several times with stirene)

 

Will do, thanks Edmundo