repairing deep scratches in hull

[23-sharkcat]

Had a few problems putting the cat back on the trailer and put quite a severe scratch between the sponsons. Any ideas on best way to fix her.

the scratch would be 200mm in length x 10mm wide and up to 4mm deep OUCH.....

[Grand_Marlin]

Has it gouged into the glass matting by much?

[gilbo]

Bugger mate - The times I dread the most, getting it on and off the trailer.

Let me know when you come to fix it, wouldn't mind watching/giving you a hand to learn myself.

Cheers

Shane

[23-sharkcat]

yer it has a little

[Blackened]

G'day
Take a picture as it will best show damage and location.

Dave

[Noelm]

Hate to be a nitpicker here, but the word "sponson" has and is constantly used in the wrong context, ask a boat builder or do a "google" on what a sponson is, it is NOT one hull of a twin hulled vessel.

[stuart]

Make up your own mind


Sponsons are projections from the sides of a watercraft, for protection, stability, or the mounting of equipment such as armaments or lifeboats , etc. They extend a hull dimension at or below the waterline and serve to increase floatation or add lift when underway.

Sponsons are commonly used on jetskis and other personal watercraft such as canoes to provide either additional buoyancy and thus stability against capsize, or hydrodynamic forces to resist capsize. They can often be easily attached to an existing craft in order to improve its stability.

On ships, they are far less common than such stabilizing means as pontoons, outriggers and dual hulls, due to their comparatively poor performance in stabilizing large hulls. However, sponsons are sometimes added to improve stability when ships are modified.

Sponsons are used on the fuselages of flying boats. They take the form of a short wing which when travelling through the water provides hydrodynamic stability during take off and landing.

The term "sponson" for armament mounting is sometimes used for land vehicles as well, such as the WWI Mark I tank. In the case of the Bradley Fighting Vehicle, which doubles as a troop transport and armament platform, the sponson refers to the aspect of the vehicle body directly over the tracks and includes layers of hardened, bullet proof materials to protect the occupants

Stu

[23-sharkcat]

thats not the response I was after. Sound like I offened someone.

I have a scratch in one of my hulls on a twin hulled vessel. what ever that may be called? :-[

I will take a photo and post it.........

[Blackened]

G'day
Haha c'mon guys, give it a break :P

Thanks 23sharkcat, the picture will be much better.

Dave

[Noelm]

OK back to the question, sorry about that I am a bit of a stickler at times, if the hull is white, you can get gel coat fibre glass "putty" you just mix it up and can apply it with a plastic putty knife or something similar, and it will fill the scratch easy as, but if it is not white, I guess you could colour it with pigmnet though I have not tried that, I have repaired vaious scratches and digs, in my cat "sponsons" before and am more than happy with the finish (but it is white) if it is really deep of course you will need mat and resin and stuff to repair it.

[23-sharkcat]

lucky for me it is white.

I should have a photo today some time.

[seatime]

Hate to be a nitpicker here, but the word "sponson" has and is constantly used in the wrong context, ask a boat builder or do a "google" on what a sponson is, it is NOT one hull of a twin hulled vessel.

have to agree here too, it's a another term that has been borrowed and changed.
It is a much more commonly used term now, not sure why, sponsons on a catamaran would be the duckboard sticking out between the OBs and the pods.

the hulls can safely be called pontoons, I think. :) :)

regards

[Noelm]

I forgot to add, the fibreglass putty can be used upside down with ease as it is quite thick, and if you do a good job with the application process you may need not to even sand it.

[gilbo]

Can the same fibreglass putty be used to repair extra unwanted screw holes ie: from rod holders that have been changed or hinges that no longer can be matched with the same screw pattern. I went in and asked a shop about this the other day and was given a 2 pack resin to be mixed together to use. Is this the same stuff or are we talking a different application.

Cheers

Shane

[Blackened]

G'day
Ok,... here is what to do with the repair to obtain a professional result

If it is just the gelcoat missing:

Prep the area to be filled by wiping out with acetone and a clean and dust free rag.

Mix up your flowcoat (this is waxed unlike gelcoast) to colour of the hull and add your mekp as per instructions.

Fill the hole/gauge/scratch with a spatula of sorts, holes and deep spots you can fill with a syringe.

Cover the wet flowcoat with masking tape. This will give a more level set and stop it from dripping if the repairs are susceptible to dripping out. This will also make it easier to work with once set.

When the flowcoat has completly gone off, remove masking tape and block it back with 600 wet sandpaper to gte the hape and level that is required.

Sand again with 1200 wet sand paper and then polish with a cutting compound, follow with a wax to seal.

You can also substitute the flowcoaat for gelocoat but will get a slightly different result.

If the actual fibreglass matting has been torn, this will need to be replaced with some chopped strand and woven matting with polyester resin. Then follow with the flowcoat/gelcoat.

Dave


R.S. Follow Grand_Marlins advice... he's the real pro at this

[banshee]

Cruise Craft use someone "just down the road" from them at Hemmant,would no doubt be dearer than fixing it yourself but their finish is as near to perfect as you will get,you would have to phone Cruise Craft to get the bussiness name.

[FNQCairns]

You could consider epoxy as a patch, contrary to popular belief it can be gelcoated over although if you would rather a 'repair' then a good proportion of the surrounding good glass will need to be feathered along it length and new glass laid in sealed and the gelcoated and buffed up -expensive.
Epoxy is entirly water proof and will seal of your bare strands (most important).

Most places will use a basic polyester resin where on any boat I own I wouldn't. If you do go the repair route specify Isothalic polyester resin and/or vinyl-ester these are much more capable and will seal of the open chop strands better than an over the counter basic resin putty or basic polyester resin no matter how it is applied.
If patching go epoxy.

cheers fnq

[23-sharkcat]

here it is.............

http://i66.photobucket.com/albums/h258/rxv3000/DSC00117.jpg

[Noelm]

gilbo, it is perfect for patches to screw holes and the like, I have used it heaps of time, just had a look at a catologue and it is $18.50 for a container with hardener, and comes in White only, very easy to use.

[Noelm]

just remember though that it is NOT for structural repairs, just small holes and scratches and stuff.

[Grand_Marlin]

23-Sharkcat,

Dont worry mate, it's not terminal.

Have you still got my number? I will drop a bit of stuff in it for you.
I have been meaning to catch up and have a look at your boat, so now will be a good chance ;)

Guys, this scratch is not deep enough to affect the structural integrity of the boat.

It will simply be a clean up and fill with Flowcoat.

Why Flowcoat? ... well it is flowcoat that has come out of there, so why would you want to put anything else back in it?

Note: Flowcoat is gelcoat, but it has wax and styrene in it to make it set up hard in a few hours ... not a few weeks like straight gelcoat would .... gelcoat will stay sticky for ages - that is what it is designed to do.

Noelm ... It looks like you were barracking for Skaifey too ;D ... just let it go mate, what has happened has happened .... no point trying to upset the twin sponson brigade ;D


BLACKENED IF YOU MENTION GELCOAT AND FLOWCOAT EVER AGAIN IN THE SAME BREATH FOR EXECUTING A REPAIR LIKE THIS I AM GONNA HAVE TO SERIOUSLY HURT YOU >:(


The fibreglass fillers mentioned above can be used, but they are absolute $hit.
They never match the colour properly (more a beige or off white colour when you put them against white gelcoat)
They are a real grainey finish, have a tendancy to shrink and seem to look worse with time.

FNQ Cairns - you can do what ever you like, but putting flowcoat over epoxy is not smart.
They will bond together, but have different expansion / contraction rates and will nearly always develop a crack around the outside of the repair.

You can put epoxy over gelcoat / flowcoat , but not gelcoat / flowcoat over epoxy.

If you use flowcoat, and do it properly ... you can get a finish like this.

Cheers

Pete

[Grand_Marlin]

And after....

[finga64]

Nice pete :)

[gilbo]

Thanks for the explanation Pete - those sort of holes are precisely the sort of thing I am wanting to fis, along with a few bigger ones for instruments and cables that are no longer used. What I was sold to do the job was a 2-1 ratio mixture of epoxy. Should I be using something else and is it the sort of job I should be attempting myself.

All this talk of gelcoat/flowcoat/epoxy has confused me a little.

Sorry for the stupid questions but thanks if you can answer them for me.

Cheers

Shane

[23-sharkcat]

no Pete I can not find your number.

Can you PM it to me again....

Cheers Mate

[Grand_Marlin]

G'day Shane,

If the holes are any bigger than 10 or 12mm diameter, then you cant just bog them up.

You then have to put a couple of layers of chopped strand fibreglass mat over the back of the holes before you bog them up.

This isn't a really hard process... just fiddly, but it does pay to have a little experience before attempting it.


Ok ...

Epoxy resins and fillers are a 2 part (epoxy and hardener) that can be used for filling scratches / chips.
It is easy to use, as it has the consistency of toothpaste, but it has a bad colour match to existing gelcoat, and it has a rough or grainey finish to it when sanded back.

Gelcoat is a polyester based product (not an epoxy), generally thick and white that is mixed with around 2% catalyst (or hardener) to make it set.
When a fibreglass boat is built it is done in a highly polished mould.
First they spray the mould with release agent (to stop it sticking to the mould, to take the stickiness out of the gelcoat when it cures, and to give the shiney finish to the gelcoat.

Gelcoat is then sprayed in the mould about 2mm thick, and is left to cure.
If you touch gelcoat in the mould after it has cured, it still feels sticky or tacky. It is designed like this so as the next process of laying in the chopped strand mat will readily stick or bond to the gelcoat.
If you were to use gelcoat in a repair like 23 sharkcats, it would stay tacky for weeks and you couldnt sand it properly ... it would be like trying to sand half dried out toothpaste.
The gelcoat is only for cosmetic purposes, and has no structural strength at all ... it is virtually just a glorified paint.

Gelcoat can be polyester based (most common) or Vinylester based (less common)
They both do the same cosmetic job of making the boat look shiney and white, but the vinylester is a newer, better and more expensive product.
The vinylester is of best use on boats that will spend their life moored in the water ... it tends to be a lot less permeable that is polyester based resin.

Flowcoat is essentially the same product as gelcoat, but it has liquid wax and styrene added to the mix. It is also mixed at 2% catalyst.
When the flowcoat cures, the wax rises to the top and seals off the flowcoat so as it goes hard and can be readily sanded.
The wax and styrene is in some ways doing what the release agent does in a mould.

Chopped strand mat.
Also referred to as fibreglass mat is the white mat that looks like it is made up of a heap of woven fibres.
A different type of polyester resin is mixed with 2% catalyst (hardener) and is used to wet the mat and stick it all together.
This resin is blue .... and it goes a yellowy brown as it goes off or hardens.

So, to put it in easy terms.

Epoxy - for a quick fix on scrapes or chips in your gelcoat.

Flowcoat - to fix any scrapes or chips in your gelcoat, and return it to looking like new.

Gelcoat ... only used if making fibreglass products in a mould.

Chopped strand mat/ polyester resin - this is the structural part of any fibreglass product.

Did this help?

Cheers

Pete

[Blackened]

G'day
Thanks for the clearing up of gelcoat and flowcoat pete. I get mixed up sometimes, but have used both before in repairs. Now I see why everyone loves you around here ;)

Dave

[Grand_Marlin]

:-*

[troy]

:-*
I now know why you love cats ;D ;D ;D
Troy

[Grand_Marlin]

;D ;D ;D

very funny

;D ;D ;D

[finga64]

I think you got him with a slam dunk on that one Troy. ;)

Thanks for the quick definitions Pete. Cleared up a few things in my tiny brain. :)

[gilbo]

Thanks very much for the advice Pete - very informative and extremely helpful.

Seems epoxy will do what I want as the areas I am fixing are quite small and the finish on them is not all that important.

Thanks again.

Cheers

Shane

[mcgilld]

Grand Marlin (Pete?).
I've read a couple of threads where you've advised on repairs and it's always great advice.
Can you supply any thoughts on Gel(/flow!)coat repair putty (note -not fibreglass filler, just the thickened white polyester based paste mixed at 50:1).
I've used it fairly extensively and it comes up like your photo when colour matched, sanded up and pollished. I haven't tried using flowcoat for repairs, only for painting. Is it easier to use than the paste or less prone to shrinkage or what?

Dave

[Grand_Marlin]

G'day Dave,

Gelcoat repair putty is a similar thing to the epoxy.

epoxy fillers seem to be better than polyester fillers - better strength and adhesion... and possibly water proofing (but that doesnt really matter on a boat stored out of the water)

The polyester fillers are a lot finer grained and sand up better than epoxy.

It is a lot easier to use than flowcoat, as it is a paste.

The K & H brand is not too bad, but the colour match over time with UV affecting it still isnt as good as flowcoat.

I go back to my original quote ... if you take flowcoat / gelcoat out, then it makes sense to put the same material back in.

Each to their own I suppose Dave.

I am definitely not saying dont use epoxy / polyester fillers, but in my experience flowcoat will still give a superior finish and better colour match.

cheers

pete

[Fiji_fish_head]

grand marlin, i have a quite a few flowcoat stains on my white fibreglass gelcote, can i use acetone to clean the flow coat paint flecks off the gel coat?? some one told me that it is bad for the gelcoat! is this true??

[hussy]

i have always used automotive putty ( bogg )to fill the holes and scratchesthen with small roller cover with gelcoat then sand when dry . has never cracked or come out, hubby

[Stu]

Hi Grand Marlin,

Im also in the process of getting rid of a few gel coat scratches (not deep).

I can see where you are coming from with gel coat. It takes ages to cure and is really time consuming to work with.

The thing that worries me with the flow coat is the wax.
What happens if I need to apply another coat of flow coat.

Should I sand the first flow coat with fine wet and dry paper before adding another flow coat or is it ok to apply a second directly over the first.

Many thanks for the info in the above posts. Its very greatly appreciated.

Cheers
Stue

[Dignity]

this thread should become a sticky - keeps getting raised over and over and Pete spends a lot of time going over the same ground


Hi Grand Marlin,

Should I sand the first flow coat with fine wet and dry paper before adding another flow coat or is it ok to apply a second directly over the first.

Many thanks for the info in the above posts. Its very greatly appreciated.

Cheers
Stue

sand Stue

[Grand_Marlin]

G'day fish head.
Acetone wont hurt gelcoat ... just make sure it hasnt been painted as acetone will affect paint given enough time.

I dont know if acetone will shift flowcoat splatter - doubtful I think.


Hubby,
We use the same stuff for minor touch ups before painting a boat, but not before gelocat.
As I said - each to their own.


Stue,
I overfill my repair then sand it back .... then if it needs a touch up for air bubbles etc I give it a guick hit with the Dremel grinder, then wash with acetone.
But, I have also given freshly cured flowcoat a good wash with acetone and filled straight over it with no apparent problems.


Cheers

Pete

[Stu]

Hi Grand Marlin,
Many thanks for that Pete,
I know it was a dumb question but its the one thing I wasnt sure of.
Its a bit tricky over filling when fixing scratches on the bottom of the hull.
Cheers
Stue

[Adamy]

OK... can I ask a really dumb question? For fixing small scrapes I should use flowcoat right? so with colour matching - how does that work? Do you get colour tubes like you might for colour matching wall paint? or get the flowcoat pre-coloured?

AND most importantly where do I get flow coat from??

Thanks,

Adam

[mcgilld]

Thanks Pete - you ought to start charging!


Fishhead - don't want to sound like a savage but you just might be able to 'pop-off' paint flecks with a sharp good quality chisel as it doesn't take that well to a non-sanded surface - being very careful of course...

Dave

[Grand_Marlin]

Stue ... use a 5ml syringe - that is the way to do it upside down ;D

Adam, If it is white, dont try and tint it, leave it white.
Colour matching is a whole new ball game, and a bitch of a job.
You then buy "natural" colour flowcoat (not white) and buy small containers of pigment.
These are all available from any chandlery, such as Bias Boating.

Also, if possible, go back to the manufacturer and ask for some of the same colour gelcoat ... this can save your ass bigtime if it is possible.

Dave ... I have all the accounts printed ... all I needis your addresses so I can post them ;D ;D ;D

Maybe I should run a workshop on gelcoat repairs ... charge a carton entry and fire up the barbie as well :)

Cheers

Pete

ps - only too happy to help :)

[Fiji_fish_head]

send me the dates!!! i'm on me way with me carton!!!!

[gilbo]

Yep - I'll be there as well, think your boat is only up the road from mine anyway Pete....

[Cruize]

Hery Blackened -that is a great how to sheet - thanks

Does that process work for cruise craft hulls? I have heard that they have a different finish and compound.

[Blackened]

G'day Cruize
No worries on the how too. What have you heard in regards to cruise craft?

Ive detailed many an explorer and outsider, they are still fibreglass boats, that is have gelcoat finishes. Treat them the same as you would a haines, kevlacat, azimut, princess, whittley or ocean alexander.

Dave

[Adamy]

A carton?? thats pretty cheap entry... count me in ;D ;D

Adam

[Blackened]

G'day


Hey Pete!!!! I'll supply the jumping castle!!!


Dave

[Cruize]

G'day Cruize
# #No worries on the how too. What have you heard in regards to cruise craft?

Ive detailed many an explorer and outsider, they are still fibreglass boats, that is have gelcoat finishes. Treat them the same as you would a haines, kevlacat, azimut, princess, whittley or ocean alexander.

Dave

Dave I heard that my Cruise Craft has a special mix on the gel coat - but it looks normal to me.

Thanks mate - if you don't mind I'll ask more questions after I have had a go detailing my boat - unless your looking for work and want to take on the job! It's just scratches and small dings.

[Blackened]

G'day Cruize
the only "special mix" in the gelcoats i'm aware of is glitter, the stuff that alot of ski and wake boarding boats use to spunk their rigs up. It looks great but when l;eft out in the sun, you will never get it back if oxidation is too deep. Feel free to give me a call if you need any help, 0421 802 691

Dave

[Dignity]

Stue ... use a 5ml syringe - that is the way to do it upside down #;D



Maybe I should run a workshop on gelcoat repairs ... charge a carton entry and fire up the barbie as well #:)

Cheers

Pete

ps - only too happy to help #:)

too cheap - will pay the price and help cook as well -where and when

[marco]

Hi , just to add to this topic i had filled a gouge with gel coat putty and it stood out really bad due to the color match was not even close , i then got grand marlin to have a go at it with the flow coat and i cannot even see where it was , a very impressive repair job , thanks again pete .
cheers
mark

[Grand_Marlin]

G'day Mark,

Pleased to help out.

I hope this highlights the difference between repair putty and flowcoat.

Cheers

Pete