Can I use CSM for the whole transom job??

[Intermediate Mariner]

Morning Gents,
I had posted another thread asking about cloth and guys said to use CSM for first layer and then woven roving for other layers (or maybe even biax) for transom. That advice is probably the best and would normally have been followed.

But... I went to my local fiberglass supply this morning. He indeed had the roving (for $26/yard) but he also had some pretty nice real thick CSM. He talked me into the CSM for tabbing the transom to the hull for the whole job. He said I didn't need the roving unless I was building a race boat or ocean liner and was pretty adamant about it! He said he's been doing this 30 years.

Can I use the CSM for the job (encasing transom and tabbing to hull)?? I plan to do 4 good layers which should end up about 1/2" thick. I also plan to bring around 6" on each side and bottom.

Will this work? I am working with a 16' Red Fish with 16" high and 66" wide transom that will hold a 40hp evinrude.

Thanks guys,

Shawn T
Wichita, KS

 

[Woodonglass]

Re: Can I use CSM for the whole transom job??

First off, It doesn't look like you put any resin on your plywood before you installed it. If not, WHY NOT!!! You really should have soaked it with resin Put the 1708 biax cloth on both sides and edges and then made some peanut butter(check this out http://forums.iboats.com/showthread.php?t=234392&page=76) to adhere it to the exterior transom skin. Your Fiberglass guy has probaby never done a transom repair. What's up with all the bolts thru the transom??? This will invite water to come back in and start the rotting process all over again. When you are done you should fill all of those holes with some of this stuff(http://www.right-tool.com/pcwhiteppas.html)I am not so sure you are going to slove your problem for the long term. If you are going to do it man, do it right. Check out the posts on this site on replacing a transom, study the pics and the text, do your homework and then dot the job right. I just hate to see you go to this amount of work, spend your money and then in a year or two have the exact same problem.

We are here to help but slow down and do it right. All the guys on this site have "been there and done that" so you shouuld listen and learn from them.
Their methods have been tried and proven to work. If you follow their advice your outcome will be successful!!!!!

 

[bigredinohio]

Re: Can I use CSM for the whole transom job??

Morning Gents,
I had posted another thread asking about cloth and guys said to use CSM for first layer and then woven roving for other layers (or maybe even biax) for transom. That advice is probably the best and would normally have been followed.

But... I went to my local fiberglass supply this morning. He indeed had the roving (for $26/yard) but he also had some pretty nice real thick CSM. He talked me into the CSM for tabbing the transom to the hull for the whole job. He said I didn't need the roving unless I was building a race boat or ocean liner and was pretty adamant about it! He said he's been doing this 30 years.

Can I use the CSM for the job (encasing transom and tabbing to hull)?? I plan to do 4 good layers which should end up about 1/2" thick. I also plan to bring around 6" on each side and bottom.

Will this work? I am working with a 16' Red Fish with 16" high and 66" wide transom that will hold a 40hp evinrude.

Thanks guys,

Shawn T
Wichita, KS

I wouldn't be taking advice from someone selling woven roven at $26 per yard!

http://www.shopmaninc.com/specialty.html

With that said, why ask questions when you're not listening to the advice given? You're not doing the proper homework by reading up on some restoration threads. As mentioned previously, slow down and do it right!

Lastly, CSM isn't strong therefore is why it was suggest to use mat with woven roven or a biax with the cloth/mat sticted together. The cloth is where the strength is.

 

[Intermediate Mariner]

Re: Can I use CSM for the whole transom job??

I have since coated the board with resin and plan to fill the holes (have actually already started - put tape on the outside and poured resin in holes from inside).

You guys got me all worried now! So $26 a yard for roving (50 inch wide roll), is that too high then?

Yeah, the guy sold me 9 yards of mat for $40, how is that price? Looks pretty high as coompared to that US Composites link, whew.. I got screwed!

So use the mat for first couple layers and then roving. I am sure I can find another use for mat... just need to find roving now I guess.

 

[tlzimmerman]

Re: Can I use CSM for the whole transom job??

First off, It doesn't look like you put any resin on your plywood before you installed it. If not, WHY NOT!!! You really should have soaked it with resin Put the 1708 biax cloth on both sides and edges and then made some peanut butter(check this out http://forums.iboats.com/showthread.php?t=234392&page=76) to adhere it to the exterior transom skin. Your Fiberglass guy has probaby never done a transom repair. What's up with all the bolts thru the transom??? This will invite water to come back in and start the rotting process all over again. When you are done you should fill all of those holes with some of this stuff(http://www.right-tool.com/pcwhiteppas.html)I am not so sure you are going to slove your problem for the long term. If you are going to do it man, do it right. Check out the posts on this site on replacing a transom, study the pics and the text, do your homework and then dot the job right. I just hate to see you go to this amount of work, spend your money and then in a year or two have the exact same problem.

We are here to help but slow down and do it right. All the guys on this site have "been there and done that" so you shouuld listen and learn from them.
Their methods have been tried and proven to work. If you follow their advice your outcome will be successful!!!!!

I would assume the reason the bolts are there is to make sure he got good clamping pressure when he glued in the wood to the transom? Standard procedure really, seen it done lots of times on here, many guys just use screws though, but bolts do the same thing, and as long as sealed properly when they come out should be fine. We don't know what he did to the backside of the ply he glued in, and I assume he is going to wet out the front and pb the sides when he unbolts and starts the process of sealing it in. He is doing it right, and is asking questions to make sure he is doing it right...ease up on him man.


To the OP: I think most of the reason people recommend roving or biax is because it builds strength and thickness quicker than using regular CSM, and the same thickness of biax would be stronger than just CSM. That said.....I think if you use enough CSM wetted and adhered properly...it should work fine. The point is to make it stronger than it needs to be, if the CSM alone is stronger than it needs to be, and the same layup with biax or roving would be half again stronger...both will get the job done. I am debating the same thing on my stringers...pop for biax or just get enough CSM that I can get locally and just layer it up good. Guys correct me if I'm wrong, but many many boat hulls that last years are made completely using a chopper that blows chopped strand into the mold onto tacky resin...then you wet it out, then repeat, layered CSM alone is pretty strong stuff.

Not an expert...just another semi educated internet opinion, would love to hear from some of the guys like OOPS that have more glassing experience.

 

[Woodonglass]

Re: Can I use CSM for the whole transom job??

Ok answer some questions
Did you glue the plywood to the fiberglass exterior skin of the transom?
did you coat the plywood with resin before you glued the two layers together?
if Not then if you can and if you really want to do this right then

1.) remove the plywood
2.) Buy 5 gallons of resin or epoxy whichever you are going to use from US Composites. and 3 yards of 1708 Bi-Ax cloth
3.) give the plywood 2 coats of resin
4.) with the third coat lay the cloth. then apply another 4th coat on top of the the cloth.
5.) then go the page 76 of OOPS post on iBoats and get his Peanut butter recipe and glue the transom to the exterior skin of the boat using clamps and braces. Use the peanut butter to fillet in the transom and then use the left over biax cloth to tab in the transom to the sides and the hull.

Seach this site for pics of how guys have done this.

This is how to do it right.

 

[ondarvr]

Re: Can I use CSM for the whole transom job??

There were boats made with just chop (CSM), but most aren't around any more, they didn't last. It was quick and cheap to just chop everything, then push it out the door and into your driveway.

In some cases CSM is all that was used on small boats over stringers and possibly even transoms, is it right...no, but in low stress situations it can hold up. By adding roving or stitched products like 1708 the strength goes up and the weight does down, both are good things.

If the boat came with only CSM and it held up for 30 years, then it appears it is strong enough for the application in that boat and you could just replace it and expect it to last.

If I was going to re-do them (stringers or transom) and the original build used only CSM , I would use mat and roving, or 1708, I wouldn't stress over which one though, both methods will work fine.

Don't bother with multiple layers of CSM under the woven or stitched fabrics, more than one layer is just wasting resin and adding cost and weight.

 

[tlzimmerman]

Re: Can I use CSM for the whole transom job??

There were boats made with just chop (CSM), but most aren't around any more, they didn't last. It was quick and cheap to just chop everything, then push it out the door and into your driveway.

In some cases CSM is all that was used on small boats over stringers and possibly even transoms, is it right...no, but in low stress situations it can hold up. By adding roving or stitched products like 1708 the strength goes up and the weight does down, both are good things.

If the boat came with only CSM and it held up for 30 years, then it appears it is strong enough for the application in that boat and you could just replace it and expect it to last.

If I was going to re-do them (stringers or transom) and the original build used only CSM , I would use mat and roving, or 1708, I wouldn't stress over which one though, both methods will work fine.

Don't bother with multiple layers of CSM under the woven or stitched fabrics, more than one layer is just wasting resin and adding cost and weight.

Thank you for an educated opinion.

 

[Woodonglass]

Re: Can I use CSM for the whole transom job??

Guess you are not going to answer the questions!

Do it your way then.

 

[83mulligan]

Re: Can I use CSM for the whole transom job??

Guess you are not going to answer the questions!

Do it your way then.

He's got the info he asked for. Let him make his decisions without you standing on his chest.

 

[Intermediate Mariner]

Re: Can I use CSM for the whole transom job??

Ok answer some questions
Did you glue the plywood to the fiberglass exterior skin of the transom?
did you coat the plywood with resin before you glued the two layers together?
if Not then if you can and if you really want to do this right then

1.) remove the plywood
2.) Buy 5 gallons of resin or epoxy whichever you are going to use from US Composites. and 3 yards of 1708 Bi-Ax cloth
3.) give the plywood 2 coats of resin
4.) with the third coat lay the cloth. then apply another 4th coat on top of the the cloth.
5.) then go the page 76 of OOPS post on iBoats and get his Peanut butter recipe and glue the transom to the exterior skin of the boat using clamps and braces. Use the peanut butter to fillet in the transom and then use the left over biax cloth to tab in the transom to the sides and the hull.

Seach this site for pics of how guys have done this.

This is how to do it right.

Thanks for the info Wood.
Here is what I did:
>First I test-fitted both pieces and drilled the bolt clamping holes. I then removed the 2 pieces and seal coated with the US 435 resin then after those dried I coated both again and clamped overnite outside of boat. I did it like this because I did not think I would have enough work time to sandwich them AND glue them to the skin.
>That peanut butter would have been just the thing. What I did though is sealed the back side of the transom board and also coated the skin and then clamped and bolted overnite. I also used the green dura-glass jelly on the bottom edge of the transom in the channel where it fits.
>Before I coated inside side of transom with mat I sealed the board. I also applied duck tape to the outside skin, raised the boat to about 45 degrees and then squiirted resin in the holes with a syringe and they filled up nicely.
>I coated everything with mat 6" around and wet it out good.
>I guess I am going to order roving or biax at this point. I would like to do 2 layers on the edges where it tabs to hull.

Your tips to "do it right" do sum it up nicely. So one layer of biax is strong enough then I gather?

Thanks
Shawn T
Wichita, KS

 

[Intermediate Mariner]

Re: Can I use CSM for the whole transom job??

Thanks to all for the replies. I will look at the all links again.

From the posts here it looks like 1 layer of CSM is in order under woven. I have that layer down so would biax be overkill on CSM? Would 2 layers of woven be overkill? I plan to install a ladder also and just want it strong.

Thanks again for everyone's input.

Shawn T
Wichita, KS

 

[Woodonglass]

Re: Can I use CSM for the whole transom job??

1 layer of biax is plenty.

 

[NSBCraig]

Re: Can I use CSM for the whole transom job??

There were boats made with just chop (CSM), but most aren't around any more, they didn't last. It was quick and cheap to just chop everything, then push it out the door and into your driveway.

Actually most the boats people are fixing on this forum are chop gun boats, and the majority of low priced boats made today are too.

One well know boat made only with a chop gun- Boston whaler.

 

[jonesg]

Re: Can I use CSM for the whole transom job??

Guess you are not going to answer the questions!

Do it your way then.

Calm down, sheesh..you're a pistol

Many of us do it our own way.

Carolina skiffs look like mat hulls too.

 

[jonesg]

Re: Can I use CSM for the whole transom job??

Actually most the boats people are fixing on this forum are chop gun boats, and the majority of low priced boats made today are too.

One well know boat made only with a chop gun- Boston whaler.

Yeh but the whaler hull shape is different from an open hull style, its basically a shovel shaped I beam , the outter and inner moldings cored with foam make for great strength.

 

[ondarvr]

Re: Can I use CSM for the whole transom job??

Actually most the boats people are fixing on this forum are chop gun boats, and the majority of low priced boats made today are too.

One well know boat made only with a chop gun- Boston whaler.

Yes most boats are made with chopper guns, that wasn't point, it was that they don't use "only" chop. There are layers of roving or biax throughout the hull. Some decks may still be only chop, but the shape and contours tend to strengthen them enough to survive.

 

[Peteco]

Re: Can I use CSM for the whole transom job??

It's not just a strength question, but a toughness or durability question.

The tensile strength of CSM versus woven roving isn't too different (22kpsi versus 40kpsi) as a finished laminate with resin. But the CSM fibers are shorter which makes the laminate less able to transmit a large impact load or dynamic load over a large area. And that's the strength of composite construction that's most advantageous.

I too would be tempted to at least tape the seam with biax before throwing down CSM. Think of CSM as a substitute for chopper gun application of fibers. Builds bulk but not as strong. Whether or not it would suffice in your application would require at least some rudimentary load calcs, but as cheap as these fabrics are just order some e-glass and throw it down. The peace of mind alone will be worth it

ETA: One thing to keep in mind is that most CSM is only polyester compatible. You can find epoxy-compatible CSM but it's likely that it's not what you bought.

 

[ondarvr]

Re: Can I use CSM for the whole transom job??

quote "The tensile strength of CSM versus woven roving isn't too different (22kpsi versus 40kpsi) as a finished laminate with resin"

Using your numbers, you do realise that 40 is about double 22, so the the laminate strength with roving is twice as strong as chop only, they aren't even close.

 

[Peteco]

Re: Can I use CSM for the whole transom job??

quote "The tensile strength of CSM versus woven roving isn't too different (22kpsi versus 40kpsi) as a finished laminate with resin"

Using your numbers, you do realise that 40 is about double 22, so the the laminate strength with roving is twice as strong as chop only, they aren't even close.

Good point - I was thinking 32, not 22.