Butt cat 18ft6

Hi Gents

I've recently taken on a new project - that being an old butt cat 18ft6 that I would like to rebuild. This would be the first time doing a boat refurb so any advice especially from guys that have done similar builds would be great..

First things I need to attend and have questions about are :

1. New deck - should I use marine ply with glass or nidacore? Any tips especially for working with nidacore would be much appreciated..

2. I suspect the original foam is waterlogged and I would obviously want to redo this - should I replace it with PU foam or go with sondor foam? I'm leaning towards the latter as I like the idea that the sondor does not take on any water or get saturated should any water find itself inside the hull.

Question - Does the PU foam offer structural support hence the reason it is used by the manufacturer AND if so and I use sondor instead would I need to add additional transverse and longitudinal framework/bulkheads under deck to increase structural support with absence of the PU foam.

3. Would it be advisable to reinforce the inside of the hull with a layer of fiberglass or maybe a coating of pool coat? Maybe both?

Any advice or ideas would be much appreciated.

Thanks in advance

Mic

Not that I know anything but apparently Len @ Butt Cat is very helpful with rebuilds..and a great guy.

http://www.buttcatsales.co.za/contact-us
I know that I fish off a few..one a brand-new/second-hand rebuild that they did themselves in PE ..what a pleasure!

Big Mic wrote:

Hi Gents

I've recently taken on a new project - that being an old butt cat 18ft6 that I would like to rebuild. This would be the first time doing a boat refurb so any advice especially from guys that have done similar builds would be great..

First things I need to attend and have questions about are :

1. New deck - should I use marine ply with glass or nidacore? Any tips especially for working with nidacore would be much appreciated..

2. I suspect the original foam is waterlogged and I would obviously want to redo this - should I replace it with PU foam or go with sondor foam? I'm leaning towards the latter as I like the idea that the sondor does not take on any water or get saturated should any water find itself inside the hull.

Question - Does the PU foam offer structural support hence the reason it is used by the manufacturer AND if so and I use sondor instead would I need to add additional transverse and longitudinal framework/bulkheads under deck to increase structural support with absence of the PU foam.

3. Would it be advisable to reinforce the inside of the hull with a layer of fiberglass or maybe a coating of pool coat? Maybe both?

Any advice or ideas would be much appreciated.

Thanks in advance

Mic

Click to expand...

MY 2cents!!!

1. nicadore seems to be the in thing as it cannot rot.
but a properly treated marine ply which was sealed with resin should outlast most things.

2. pu foam is good, but sealing the hull is where most f ups come in.
pu foam does add strength and stiffness to the hull.
sondor is loose sections so no adding of strength to the hull.
so adding cross bars etc will be a benefit.

3. I would even go to 2x layers even 3x, you are not adding so much weight so the added extra layers will add strength to the hull.
pool coat is similar to gel coat.
it is very hard and it does crack easily if not supported.
so just normal 2x layers of fabric would be good.

adding 50 kg or even 80kg to the existing hull on improvements will not make a huge difference.
adding such weight on a small 12ft vessel is a big problem.

also do take a look on www.boatfishing.co.za

builds have been done there and also lots of knowledge there

but do keep the updates going here, we all can learn from it

Thanks for the replies and advice gents - I will keep updating as I go _seal1_

I was today at AMT composites in Joburg .
You also have a one in Cape Town . Do it right from beginning, go and see what they have there for deck and rest . That composite material ( not nidacore - forgot name ) - It’s amazingly light - at least 3-4 times lighter then wood and very strong . It costs but the lighter boat you make the better will be ( better ride and smaller outboards ) and it does not rot . I would forget about wood - it’s just pain to seal it and it’s far too heavy. If you can get Italian plywood - that is than different story . Butt Cat is all about being light. So don’t make it heavy like a Snake Cat

For that hull you need to use bonding foam and that is a PU closed cell foam . I agree with Willem add two layers of fiberglass . They have different types of glass and they will advise you also which weave is better for that application .
They have all what you need in one shop . Rollers , fiberglass , acetone, foam , fairing compound ... etc .

Good luck - it’s a huge job you doing , but go slow and take time. Remove deck and all foam - make new stringers and so on .... Friend and myself are re doing deck on Seacat - sanding , fixing all crap job by boat builder and previous owner . Preparing for Line-X deck coat . Job just does not end . But that is when you owe the boat . But at the end you will do a proper job without taking shortcuts and your boat will last you for long . What I have seen in past I came to conclusion that no boat Bulider can do better job then myself, neither I will ask any of them anymore to do anything on my boat as I have seen kak job like you cannot believe . Internet and Sealine is your best friend and best knowledge base - rest is your elbow grease and healthy Bank account .
Just my 2c

Pm me, I see we in the same area, I dont mind coming around and giving some advice on your build!

the best would be to use epoxy and not polyester resin!!!

epoxy does not absorb water at all.
but too expensive.

but on the inside of a hull it is not needed as no water should be present inside the hull

1. New deck - should I use marine ply with glass or nidacore? Any tips especially for working with nidacore would be much appreciated..
Nidacore or a similar honeycomb material. Layer both sides with glass and remember to put in backing plates where necessary.

2. I suspect the original foam is waterlogged and I would obviously want to redo this - should I replace it with PU foam or go with sondor foam? I'm leaning towards the latter as I like the idea that the sondor does not take on any water or get saturated should any water find itself inside the hull.
I suggest bottles in plastic nets along the keels and then Sondor blocks on top.

Question - Does the PU foam offer structural support hence the reason it is used by the manufacturer AND if so and I use sondor instead would I need to add additional transverse and longitudinal framework/bulkheads under deck to increase structural support with absence of the PU foam.
Foam does not offer much structural support. It does lend some rigidity but you should be adding stringers.

3. Would it be advisable to reinforce the inside of the hull with a layer of fiberglass or maybe a coating of pool coat? Maybe both?
Yes - even 2 layers would be OK

Hi Gents

Thanks a mil for the responses - really did not expect so much feed back!

I've got a fairly good idea about how and what I would like done with the rebuild.

I've decided on 2 layers of glass on hull inner, nidacore and glass for the stringers and bulkheads and then nidacore decking.

I am still in 2 minds about what floatation I should use...I will do some more research and decide upon an option...I think there is plenty time to decide before we get to the point where foam needs to be added.

Also I've decided not to take this project on alone and will be having a local boat builder be doing some of the work and will assist where I can and be as involved as possible in the project.

I will be taking the butt cat into the work yard next week and will update from there..

This is what she currently looks like - first thing I will be doing is cutting the chariot / fwd console off.

if you search this forum you will see that way back Fanie advised using sondor foam.
only later did the guys see the value in his post.

in any case,

sondor foam does not absorb any water and it will not rot.
so this will allow you to have bungs in the hull.
as soon as a water leak is detected one can attend to it.
the hull can still drain the water out the bungs!!!

pu foam will absorb water when the seal is broken.
and it only becomes worse.

and don't worry about having proper bottels!!!
if you like.
and don't worry about holing your hull.
to hole a hull is not easily done.
take a hammer to a hull and see if you can penetrate it?

to make a big enough hole, for bottels to float out...….I would not think that you would still be on the boat.
you would be flying through the sky if you manage to hole the hull big enough for bottles to escape.

it is said, that most of the leaks are from above deck and not the keel strips as such.
keel strips, through the screws over time with beech work.

but it is your decision at the end of the day.

but keep posting the pics and work done, we all can learn through this exercise!!!

all the best

From what iver read in numerous sources is that buttcats have thin hulls and therefore they need Pu foam to strenghten the structure. But if you add 2 layers of glass to the hull then you shoul be able to use sondor. Make sure you have enough stringers and bulkheads. 18mm nidacore with 2 layers each side is more then enough for stringers, bulkheads and the floor. Tip to save some resin when working with the nidacore is to take a roller and resin to seal the fabric first. Then when its sticky or hard you start adding the layers. Otherwise the resin will flow out of the glass and into the cavities while working over the glass

Update : Day 1

Started removing the aft section of the deck - this was completely rotten and I managed to remove most of it with a koefoet.

Next I removed the chariot console and forward section of deck and top deck that was newly rebuilt by previous owner ( lots of cutting required).

After the whole topside was removed I started breaking original stringers and removing foam, which was completely saturated with some big cavities as well that held alot of water.

I managed to remove about 95% of the foam and bhd's and stiffeners until I became exhausted - hell of a job man alone 😅

Tomorrow I will continue and get hull prepped and ready to sand down for application of extra glass layers.


Pics to follow...

Aft section of deck removed

Chariot and fwd top deck section removed

Foam almost completely removed

For the bulkheads and stringers I have decided to use 25mm nidacore all round - same for the deck. This will probably bring the costs up a little but it's always best to slightly overbuild things IMO.

I have decided to use sondor even though many have advised to use PU - after seeing the state of the PU in the hull today..... Hell no!


I think with the hull being reinforced with 2x layers of glass and the stringers and bulkheads being overbuilt that things should stay together nicely.

That transom is propably also rotten. Just make sure before you start rebuilding. Sterkte! Its a shitty job but very rewarding in the end. Check my post "16ft acecraft makeover" My boat was just as rotten but looking at the boat today i am very proud

Foxstrike wrote:

That transom is propably also rotten. Just make sure before you start rebuilding. Sterkte! Its a shitty job but very rewarding in the end. Check my post "16ft acecraft makeover" My boat was just as rotten but looking at the boat today i am very proud

Click to expand...

Thanks Foxstrike, I have looked at your rebuild post many times for ideas and info👍🏻👍🏻

We pulled the transom out today and will be redoing that - it was still pretty solid but I think redoing everything one time will be best!

Just a little update...

The hull is finally fully prepped for glassing - sanded down glass and excess resin with a stone disc as well as a flappy disc of 80 grit. All I can say is thank goodness - it's taken me about 3.5 days of cutting, sanding and grinding to get the boat to this point.... Not to mention I've burnt out 2 small grinders lol.

Inner keel strips removed as well - these were wood beams with glass over and were saturated with water. I will be reinforcing keel inner with maybe additional layers or glass or with a resin mixture.

Waiting for some materials to arrive before we can start the glassing of the hull. We've ordered 225kg of resin and 45kg roll of chop strand 450gr to start with.