1971 20 SF Transom project
 

Well, its about time I start working on this boat if I want to get it done by next spring. I am first beginning with the transom, then I plan on raising the deck and doing other fun and exciting things with her!!! lol.

So far, I have cut out the back of the boat and removed the wood the was previously there. By the picture, you can obviously tell it wasn't in the best condition to say the least.

In the next couple of days, I plan on finishing grinding/ sanding down the inner fiberglass.
Does anybody suggest any particular type of grinder I should use for that..?? And, does anybody have any suggestions on how to get the white crap off the went on the sides and bottom wood in the transom....that is some hard stuff!!!


I also plan on using Douglas fir for the transome....does anybody have any reasons why not too????

Also, I have a couple quick questions on some other random stuff about the boat:
My boat doesn't have any type of core under the gunels, and i thought it was kinda wierd cause most boats do...right??

My sf doesn't have any foam under the deck. I thought that most seacrafts had foam under the floor. Or is that only MA's??

Also, I want to use the talk it came with because its in good condition and I was wondering if anybody knew how many gallons it is. Its the tank that went under the console.

Thanks in advance guys
-Andrew

http://i40.photobucket.com/albums/e2...o/P1010037.jpg

http://i40.photobucket.com/albums/e2...5/P1010037.jpg


Here is the crazy hard white stuff I can't remove...
http://i40.photobucket.com/albums/e2...o/P1010039.jpg

Re: 1971 20 SF Transom project
 

Well I'll be darn. I asked on another thread if anyone tried removing the wood core on the transom from the inside and didn't get a response.
What made you try this method?
Can you show a picture from the stern? Do you plan on building the transom up higher or close the whole thing in?
Your question on the fir. Better off using a high grade marine ply. As for a tool someone suggest a Fein Multimaster
on another thread in this section.Never used one myself but will try it out soon. Where are you located? Keep us updated with the progress

Re: 1971 20 SF Transom project
 

Quonie,
I am doing it from the inside because I plan on puting a new floor in and reconstructing the livewell and bilge access area, so why cut up the outside of the boat when I am going to cut up the inside?
I will get a picture of the stern as soon as a get a chance.
I plan on raising the transom 5in.
thanks for the responce

Re: 1971 20 SF Transom project
 

Does anybody suggest any particular type of grinder I should use for that..??
http://www.casdvm.com/photos/DSCN3356.JPG

http://www.casdvm.com/photos/DSCN2646.jpg

dougfir is soft and holds moisture. Also I dont think they make sheets big enough to cover the entire transom. Use marine grade plywood or composite like Cosa board. air chisel works for the "white stuff"

strick

Re: 1971 20 SF Transom project
 

DougFir A/B marine ply is what I used for my transom.

Re: 1971 20 SF Transom project
 

BigShrimp,
Whats the difference between dougfir and dougfir marine ply?
Is one softer than the other?

Strick,
what type of tool did you use with that disk?...how many amps was it? Do you recomend a particular manufacturer?

Thanks for the responces.

Still looking for any info on the size of the tank I have and why nothing my boat was cored with plywood or anything.

Re: 1971 20 SF Transom project
 

A 4 1/2 inch grinder is what you need. I bought the Makita from home depot about $100. I think its 5 amps. That tool and a shop vac are two things that you cant do without. You will be using them almost every day. Happy grinding!

Re: 1971 20 SF Transom project
 

The standard is A-B Douglas Fir marine.

There is no diffrence in the wood in Doug Fir [DF] ply's and DF marine ply's, except the marine has a higher standard about void's. The marine has basicly no void's.

There are other maine plywood's. [Okoume & Meranti]

I personally would not use them as a transom core. They are more expensive and have better/smoother outer ply's.
They would be a excellent choice if you were building a whole wooden hull.

The transom core on the boat's we have is highly imbeded in fiberglass on both side's, so that super looking surface on Okoume is $130 a sheet & Meranti is $95 a sheet mean's nothing. A/B DF Marine here is $74 a sheet.
Any of these plywood's need extra attention to the end grain and any holes you bore thru it.

Re: 1971 20 SF Transom project
 

That white stuff was a PIA. Get yourself a nice quality chisel...preferably a concrete/brick splitting chisel and a hammer. Get in between the white stuff/putty and whatever surface it's adhering to and give it a few whacks. That putty SC used is very solid, very dense but also very brittle.

Lookin good Yamt125. The older SC didn't have the same arrangment in the hull as the later SC's. My 1978 doesn't have stringers like you, instead it has these "pontoon" type stringers filled with foam. For your project I'd take a look at Jason "Trayders" project and make it my template.

http://www.classicseacraft.com/Trayder/index.html

The MA I think is more comfortable and utilitarian, but the SF is a far better looking boat...much nicer lines!

Re: 1971 20 SF Transom project
 

What your talking about is resign/Cabisol mix.

Strick posted the correct tool. :) A zip gun.

http://www.casdvm.com/photos/DSCN2646.jpg

http://www.harborfreight.com/cpi/pho...2999/32940.gif

Re: 1971 20 SF Transom project
 

Looked back at he post. Sorry my bad... I thought you were talking about using doug fir planks for the transom. Your choice on transom material depends on how much you want to spend and if you are worried about a little extra weight and water intrussion. The transom's in these boats were made of plywood and they lasted 30 years. So if you re do it properly with plywood then the transom should last another 30 years. The main thing is like Bobby said you have to pay special attention every time you drill a hole in the back of your boat that you take precautions to keep the water out of the wood. I re-did my transom with plywood. It may be a little on the heavy side but it's solid. I may try that coosa board on the next transom I do....seems that is what everyone is doing these days. It is 30% percent lighter then plywood which is not really all that much weight difference if you are just re-doing the transom... if you are redoing the entire boat then it adds up.

strick

Re: 1971 20 SF Transom project
 

Will, thanks for the advice about the grinder. Tonight I just sanded out the small particles of wood the were embedded in the resin they used when the boat was made.

Wart, thanks for the information reguarding the wood. I'm iehter gonna use the regular dougfir, or the marine grade. Like strick said, if the origional lasted 30 yrs, then the new one should too. And I will deff be happy if the new one last another 30 yrs. If you think about it, in another 30 yrs, the boat will prob need another major facelift anyways, so I don't see too many advantages with going with coosa anyways.

Grady,
After seeing you start your project, It deff gave me the motivation to move a little quicker than i was before. Yours is coming along great. How do you like the results of the fairing compound you used?? I have to decied on what kind I'm going to be using for my floor and other things.
I'm deffinately gonna use trayders and marks boats as guides.

How smooth or rough should I leave the transom? Right now i'm using 60 grit paper with the orbital. Hopefully tomorrow I will finish up the sanding, and chissel away the small amount of the old cabosil mixture.

Thanks for all the responces. Tomorrow I will post new pics of the transom.
-andrew

Re: 1971 20 SF Transom project
 

Hey Yam...your project is looking great. I like the grinder Strick showed....those work great on my DeWalt 4.5 inch grinder...much better then a simple disk...only drawback is they're slightly more expensive.

I would not leave any surface which is expected to get resin on it smooth. Rough up everything as it increases surface area which intern increases adhesion.

The fairing compund I used was Interlux Interfil 830. It worked out great...it spreads and sands really nice. After I glass over the deck I basically "skim coated" the entire deck with fairing compound.

-Alex

Re: 1971 20 SF Transom project
 

Unfortionately, I woke up to rain this mornin so I will have to finish chisseling the old cabosil mixture on Monday b/c i'm going to vermont for the weekend.

So far, this is what the entire transome looks like right now. The wood looks dark b/c it is wet from the rain, but there isn't that much left to take off.

http://i40.photobucket.com/albums/e2...P1010037-1.jpg

Adios
-andrew

Re: 1971 20 SF Transom project
 

Have today and tomorrow off from work, so I went to the lumber yard and picked up 2 sheets of marine ply. They charged me 92.00 per sheet. Other yards around had similar prices so i figured it wasn't too steep. Also, got all my fiberglass supplys from LBI in groton CT. I have to say, there website is very easy to understand if your a novice in buying fiberglass.

I just have a couple last minute questions before I start to lay it up....I plan on building up the outer skin with a couple layers of glass, and I would to know whether or not I have to wait for each layer to cure completely, or can I just wait an hour or so to lay the next on?
Here is my plan for the transom...

outerskin
1.5 oz mat
1708
1708
wood
1.5 oz mat
wood
1.5 oz mat
24 oz woven
1708
6oz cloth

Am I going overboard with all the layers of glass, or should I have more?....all opinions welcome. Thanks

Re: 1971 20 SF Transom project
 

I'd use 2 layers of 1.5 oz mat for laminating the two pieces of plywood. Make sure they are both wet.

I'd also use some more mat over the 1708 before the final 6 oz cloth layer. If not you'll end up with print-thru of the 1708 pattern.

Re: 1971 20 SF Transom project
 

Would it make any difference if the last four layers were as follows:
1.5
1708
24 oz
6 oz
Thanks for the reply

Re: 1971 20 SF Transom project
 

Are you using epoxy or polyester based resins?

Re: 1971 20 SF Transom project
 

You wrote outside skin in your post...you meant inside skin, right?

I would use more 1708 on the inner skin. But any combo you use (like the one you suggested) is going to be very strong.

Re: 1971 20 SF Transom project
 

I am using polyester laminating resins.

I mean inside skin of the transom...sorry about the confusion. Thanks

Greene, are you the same Greene some the cm site?
If so, I used your transom job as sort of a template because raybo had alot of input in it.
If you remember, How much resin did you use?
Hows your transom holding up anyways???
Do you have any advice on what NOT to do? Thanks
-Andrew

Re: 1971 20 SF Transom project
 

Forgot one more thing...
Greene, did you end up using a poly resin?
If so, what was the ratio u used. I'm a little confused on it.

Re: 1971 20 SF Transom project
 

I ended using vinylester resin. First I rounded all the corners/angles where the transom meets the bilge/hullsides with thickened resin. After I put a layer of 1708 and 1.5 oz mat on the transom skin to beef it up. I installed the new core and then I used 3 layers of 1708 and 1 layer of 1.5 oz mat to form inside transom skin. I then tabbed three overlapping layers of 1708 at the angle where the transom meets the hullsides. It feels plenty strong, especially after installing the stringer knees, but I haven't hung the motor yet as the project still continues.

Do's and do nots....
-I wish I made the transom opening smaller, but instead I just made cutout from the old transom.
-Get grinding disks from an autobody shop.
-AND round the top edges of the transom core with a roundover bit on the router before installation. This will allow the glass to over top edge of it much easier, ie glass doesn't conform well to 90 degree corners