Classic AquaSport

Aquasport Model Rebuilds, Mods, Updates and Refreshes => Other Classic Rebuilds => Topic started by: Conrad4784 on November 10, 2021, 10:27:10 AM

Title: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 10, 2021, 10:27:10 AM
New to this forum.  Thank you in advance for any advise given.  I picked up a 1971 proline flat back since they are close to the aquasports figured yall could help me out as I go through this project.  I was looking to pick up a portabracket for the proline but those things cost about as much as the entire project.  I have heard these boats run a little better with the engine setback.  The new transom is enclosed so I will need to get some kind of bracket.  I wanted to see if anyone has run a 36inch armstrong bracket with a jackplate mounted between the engine and bracket?  I could pick up both on marketplace for half the cost of a used porta bracket with less setback. any thoughts?  the engine I have is a 225hp Yamaha 2 stroke.  I'm not sure how much that will make the boat sit in the rear.   
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: RickK on November 10, 2021, 04:47:05 PM
Conrad, I'm going to move your topic into the forum where you might get advice from other Proline owners. Not blowing you off, as you said they are kinda similar, so we can and will give you sound rebuild advice.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: RickK on November 10, 2021, 05:00:13 PM
Did you do the rebuild?  Looks real nice. What is the height of the transom?
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 12, 2021, 07:30:47 PM
Thank you Rick I cant take credit for the ransom the previous owner did a good job with the glass work but got burnt out on the project and/or didn't have the time to finish.  it is a 30inch transom.  Thank you for moving the post for me. Just seeing if anyone has done a bracket with jackplate setup and if they were pleased with the ride.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Ulysses485 on November 13, 2021, 08:02:09 AM
Hello and welcome to the forum Conrad. How do you plan to use the boat and where are you located?  Porta bracket is designed to get in to the shallowest of shallows and jump out in the shallows as well. However, I feel the need is primarily those looking for tarpon, redfish, etc. and in the flats on the west coast of Florida. The shallows on the east coast of Florida and up the coast don’t seem to have as much of the same need for it because the water doesn’t have such a slow drop off as it does in the gulf. I live in north central floria and it seems people back home in Miami only know of Armstrong brackets and jack plates. Keep in mind that brackets can be made with different amounts of flotation in them so they can be made to accommodate the loading.

Hope that input helps.

Ulysses
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: RickK on November 13, 2021, 12:41:27 PM
What length FB is it? Looking at the image with your truck it seems to be a 22?
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 13, 2021, 10:22:04 PM
its a 24ft flatback
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 13, 2021, 10:36:47 PM
Hello and welcome to the forum Conrad. How do you plan to use the boat and where are you located?  Porta bracket is designed to get in to the shallowest of shallows and jump out in the shallows as well. However, I feel the need is primarily those looking for tarpon, redfish, etc. and in the flats on the west coast of Florida. The shallows on the east coast of Florida and up the coast don’t seem to have as much of the same need for it because the water doesn’t have such a slow drop off as it does in the gulf. I live in north central floria and it seems people back home in Miami only know of Armstrong brackets and jack plates. Keep in mind that brackets can be made with different amounts of flotation in them so they can be made to accommodate the loading.

Hope that input helps.



Ulysses


Thank you for the response
I fish the intercostal areas mainly st Augustine up to Fernandina.  Sometimes it gets pretty shallow but i dont run with much speed once it gets 2ft depth or shallower.   I have almost got stuck a few times with my 22ft hydrasport bay boat which drafts about 11 inches. My main concern is being able to tilt the motor up with out hitting the enclosed transom, and raising the motor when in shallow creeks fishing for red/flounder.  With that said I also fish the jetties for sheep head and whatever is biting.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Ulysses485 on November 14, 2021, 09:49:27 PM
I would think you could get away with a fixed bracket and jack plate where you are.  You wouldn’t have issues clearing the transom with a typical Armstrong bracket. Depending on when you are looking to repower, might want to scan the internet and look for a used porta bracket as they get sold here and there for 1500-2500. Keep us posted.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 16, 2021, 04:14:31 PM
Well I thought the glass work on the transom was good but it wasn't.  The previous owner did pretty good work with the 5 flayer of glass but it looks like something went wrong when he tried to install the coosa board. It was not fun grinding all of that glass out.  There are a few spots that I im going to fill with some peanut butter style resin, then glass in the perimeter, followed by 5 layers of mat over the entire transom.  then i will need to add about 3 additional layer to the bottom third of the transom because its low all the way across.  What do yall typically do for the top cap on the transom, should i leave a couple strips at the top to glass the cap into the transom.  Or do yall make your transom cap to screw in like the rest of the boat and the rubrail covers it?  Would yall wrap glass over the top of the transom even though a cap will be installed.  thanks
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Ulysses485 on November 16, 2021, 06:47:04 PM
I’m sorry to hear about the experience you are having from the previous owners work.

Regarding the build back, I would stick to 1708,1808, etc. or structural biaxial glass 1700,1800 (depends on Polyester resin vs Epoxy resin choice AND what he used….because if epoxy was used, then epoxy it is). Mat will not give you much strength and considering the exterior skin was cut out, that’s most important to build backend tie to existing. Mat is used more on parts and to eliminate fairing of weave in the cloth (used as a last layer so the surface lays out flatter). You want to wrap the transom to tie to existing exterior hull skin.
Here is a sketch I did a while back of a similar situation …

(https://classicaquasport.com/gallery/data/906/A29FFAD3-74FE-4772-9A7C-9288236448FA.jpeg) (https://classicaquasport.com/gallery/showphoto.php?photo=22232&title=a29ffad3-74fe-4772-9a7c-9288236448fa&cat=906)

Just my .02…hope that helps.

How does the inside tabbing look from the Coosa core to the sides and bottom of hull?

Ulysses
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Tampa Bay Mike on November 16, 2021, 07:34:31 PM
Oh man, that was painful to read. When I looked at the first picture I thought the glass work looked pretty good. Guess you never know until you really dive into it.

So all the coosa is ripped out now? What's left? The inside skin only?
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: RickK on November 17, 2021, 06:33:54 AM
That sucks.
IMO, to save time and effort, I would take a sawzall and cut the transom skin out instead of trying to repair it. I'd remove the Plascore knees between the transom and the Plascore inner transom (to give you some working room) and then grind everything down to prepare for new glass.
Next I would plan leaning a sheet of melamine against the aft of the boat, clamp it to the hull and then use that as a mold to build your new perfectly flat transom from the inside. You can spray the inside with PVA mold release or wax the inside so the melamine is easy to get off.
3 layers of 1708 is enough overlapped on the sides and bottom at least 3", 6" and 9" (4,8,12 is normal). Then glue/clamp in the new transom core and finally add 3 more layers of 1708 to the inside. Now you'll have a solid transom. You'll have a little fairing to do on the outside along the edges but that will be easy.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 17, 2021, 07:20:37 AM
Oh man, that was painful to read. When I looked at the first picture I thought the glass work looked pretty good. Guess you never know until you really dive into it.

So all the coosa is ripped out now? What's left? The inside skin only?

I removed the 6 layers of 1708 from the outside of the boat It is still all glassed inside the boat.  the Glass work looked okay it was when he bonded the coosa that the issues happened.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 17, 2021, 07:42:10 AM
I’m sorry to hear about the experience you are having from the previous owners work.

Regarding the build back, I would stick to 1708,1808, etc. or structural biaxial glass 1700,1800 (depends on Polyester resin vs Epoxy resin choice AND what he used….because if epoxy was used, then epoxy it is). Mat will not give you much strength and considering the exterior skin was cut out, that’s most important to build backend tie to existing. Mat is used more on parts and to eliminate fairing of weave in the cloth (used as a last layer so the surface lays out flatter). You want to wrap the transom to tie to existing exterior hull skin.
Here is a sketch I did a while back of a similar situation …

(https://classicaquasport.com/gallery/data/906/A29FFAD3-74FE-4772-9A7C-9288236448FA.jpeg) (https://classicaquasport.com/gallery/showphoto.php?photo=22232&title=a29ffad3-74fe-4772-9a7c-9288236448fa&cat=906)

Just my .02…hope that helps.

How does the inside tabbing look from the Coosa core to the sides and bottom of hull?

Ulysses

I have a couple rolls of 1708 I planned on using to repair the top cap but Ill use it for the transom and buy more.  I will need to grind away the gelcoat on the inside to check but I think it will be okay.  The floor he did has little to no air bubbles and the 5 to 6 layer of 1708 on the exterior was mostly air free it was the bond between the 1708 and coosa that went wrong.  Poly was used in the build so that's what I'm going to use for the resin.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 17, 2021, 07:59:18 AM
That sucks.
IMO, to save time and effort, I would take a sawzall and cut the transom skin out instead of trying to repair it. I'd remove the Plascore knees between the transom and the Plascore inner transom (to give you some working room) and then grind everything down to prepare for new glass.
Next I would plan leaning a sheet of melamine against the aft of the boat, clamp it to the hull and then use that as a mold to build your new perfectly flat transom from the inside. You can spray the inside with PVA mold release or wax the inside so the melamine is easy to get off.
3 layers of 1708 is enough overlapped on the sides and bottom at least 3", 6" and 9" (4,8,12 is normal). Then glue/clamp in the new transom core and finally add 3 more layers of 1708 to the inside. Now you'll have a solid transom. You'll have a little fairing to do on the outside along the edges but that will be easy.

Using the melamine sheet is how the previous owner did the transom that s why the outside looked so flat.  I believe the inside is rock solid and it was just the first coosa board that didnt get clamped down good enough to the exterior skin he made.  I'm going to drill out the drain hole to see if there is a gap between the two coosa boards at the bottom.  If there isn't I'm on the fence on ripping it all out.  Either way it will be a lot of work whether its more fairing or more glassing.  Structurally it seem solid as its sitting right now but I'm no glass expert.   
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: RickK on November 17, 2021, 10:34:11 AM
Working the transom core in from the outside and then laminating an outer skin without going around the outsides of the hull, to tie it in is tough work, requiring a lot of fairing.  That is why I suggested the sawzall approach.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on November 18, 2021, 06:30:28 AM
Working the transom core in from the outside and then laminating an outer skin without going around the outsides of the hull, to tie it in is tough work, requiring a lot of fairing.  That is why I suggested the sawzall approach.

I hear you, thank you for the info, I will most likely have to go that route.  Hopefully i can sand the glass off the other side of the coosa and reuse it.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Ulysses485 on November 19, 2021, 08:07:21 PM
On second thought, I’m with Rick. I would remove the core and salvage it if possible, and build it with a MDF mold. Do it once. I think the piece of mind down the road would be worth it alone.

I’m making a complicated mold on my 240 to eliminate any and all fairing that I can. A flat MDF board mold across a transom to build from is the way to go.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on December 08, 2021, 07:30:57 PM
So I got back to work on the project and cut the transom back out.  I started sanding the gelcoat on the inside of the transom to see the glass.  On the small part exposed the glass work looks like it bonded well.  Seems the previous owner just didn't get the coosa put in place quick enough and not enough pressure to bond it to the exterior skin.  I plan on grinding down the inside glass on the coosa just enough to verify there is not bubbles or voids, if its okay I'm going to leave the poly on the inside.  The exterior facing part of the coosa I'm going to use some thickened poly to fill a few dips i grinded and make sure its perfectly flat.  I'm going to attach a piece of waxed mdf to the back of the boat and build it back up again like yall suggested.  How do you attach the board to the back of the boat?  Screws and grind them off on the inside?  Also while in the transom is out I'm going to cut some access holes and mount some deck drains to be plumbed to scuppers.  I bought a glass leaning post on facebook and plan on glassing in a livewell/seat where the cooler sits in the pictures.  I will need to move the electrical pvc and console forward 7 inches leaving just enough space in the console to mount two house batteries.  Moving it forward will give me apporx 14inches of space between the console and leaning post.  Yall think this is enough?  behind the leaning post I will have 3 feet behind the livewell.  look at the pictures and tell me what yall think, I'm all ears if yall have anything you might do differently. 
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on December 08, 2021, 07:34:21 PM
couple more pictures
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: RickK on December 09, 2021, 06:16:53 AM
What kind of space do you have behind that bulkhead? You'll need about 18" of working space and be able to grind to raw glass along the sides and bottom in prep for new glass. I would gently cut out the bulkhead (so you can re-use) so you gain the working space you need. lay a 1x2 or 2x4 across the top of the hull sides and secure with screws/wood blocks to keep the hull shape - do this about 2 ft from the rear of the hull. Usually, you use an overlap of cloth in a 4,8,12" or 3,6,9" overlap to tie into the sides and bottom. You should do the same once the core is in and to tie it into the sides and bottom.
To attach the melamine you can glue blocks of wood to the outside of the hull and screw through the melamine and into the wood blocks to secure the melamine tightly against the opening. You'll use the melamine to form a dam to create the new 3 layers of 1708 skin. Then when you're done you can chip the wood off and grind/sand the contact points fair.
If you are going to try to salvage the Coosa core I would feel better grinding the glass off totally, then you know the condition and can laminate to it in confidence. A cheap harbor freight 7" grinder with 24 or 36 grit wheel will make quick work of removing the glass and gelcoat/paint.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on December 11, 2021, 04:18:42 PM
I can grind fine from the outside laying glass from the inside with the bulkhead there would be a pain.  I have 11 inches at the bottom and around 18 up top.  I do have a question once I lay the glass for the exterior skin are people laying an additional couple of layer in between the cutout on the back of the boat so when you put the coosa there wont be a gap.  If that makes sense.  I have 2 inches of the original exterior skin that is probably a little less that 1/4 inch.  The coosa runs the full length of the transom seems like there would be an gap unless when you sandwich you put a ton of thickened poly.  Or do you cut down the coosa to fit inside the perimeter of the original exterior skin I left?  I've tried to find some videos of someone doing a transom this way with no luck. 
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: RickK on December 12, 2021, 05:37:26 PM
The normal lay up is mix some thickened resin (chopped strand, cabosil or wood flour to a peanut butter consistency) and use a rounded tool, like a wooden spoon or you can make your own from a stir stick, etc. Use the tool to load the corners all around so there is a rounded corner (hull sides and hull bottom where the melamine meets the hull.
Before you start the "fillets" you want to have 3 layers of 1708 already prepped - lay a 1x2 across the top of the transom and drape the 1st layer of 1708 and then trim it so that you have the overlaps that you need 3,6,9 or 4,8,12 - your choice and your choice if you lay the smallest or the largest overlap first. Then spring clamp the 3 layers of cloth to the 1x2 and flip them out of the boat.
Now run the fillets and let them just start to kick, not harden. Mix the resin while you're waiting. As soon as the fillets start setting up, wet down the melamine with resin, flip the first layer of glass into the boat, wet it in with a short nap roller and hard roll it to squeeze the resin through, Repeat for the other 2 layers of cloth. You are doing this "wet on wet". When the glass hardens lightly scruff the top layer of the glass to get it ready to install the core.
Make sure you dry fit the core material where it will fit to see if you need to round off the rear most corners so they will fit and snuggle into a fillet you'll apply in the next step. To set the core for the transom 1) add a fillet of thickened resin and 2) usually you use a 1/4" notch trowel and trowel on thickened resin onto the new transom skin and then clamp the core in. I would also fill in any gaps around the core and hull bottom and hull sides and let everything harden. Next you'll be scruffing up the front of the core, prepping 3 more layers of cloth and repeat the same process you did to laminate the new outer skin.
So lets say you use the 3,6,9 overlap method, then add a 2" core and repeat the 3 layers with 3,6,9 overlap you are now out into the hull about 20+" with the glass work. You'll have a rock solid transom but it takes some room in the prep.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Tampa Bay Mike on December 14, 2021, 10:52:02 AM
I can grind fine from the outside laying glass from the inside with the bulkhead there would be a pain.  I have 11 inches at the bottom and around 18 up top.  I do have a question once I lay the glass for the exterior skin are people laying an additional couple of layer in between the cutout on the back of the boat so when you put the coosa there wont be a gap.  If that makes sense.  I have 2 inches of the original exterior skin that is probably a little less that 1/4 inch.  The coosa runs the full length of the transom seems like there would be an gap unless when you sandwich you put a ton of thickened poly.  Or do you cut down the coosa to fit inside the perimeter of the original exterior skin I left?  I've tried to find some videos of someone doing a transom this way with no luck.

I laid three additional layers of 1708 in the cutout area when I raised mine from a notched 25" transom to a full height to bring it flush with the existing skin. Then I did three full layers overlapping the bottom and sides - coosa - and three final layers on the inside. It's the same principle with yours except that your "notched area" is pretty much the entire back of the boat since it was all cut out. I would think that if you don't want to go that route then you could taper in a few layers to a foot or two to make it a smoother transition. Or maybe a combination of a taper plus one or two layers.

I can't imagine you'll want to do this a third time so the investment in the extra work and glass now may be worthwhile.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on December 20, 2021, 12:09:24 PM
I can grind fine from the outside laying glass from the inside with the bulkhead there would be a pain.  I have 11 inches at the bottom and around 18 up top.  I do have a question once I lay the glass for the exterior skin are people laying an additional couple of layer in between the cutout on the back of the boat so when you put the coosa there wont be a gap.  If that makes sense.  I have 2 inches of the original exterior skin that is probably a little less that 1/4 inch.  The coosa runs the full length of the transom seems like there would be an gap unless when you sandwich you put a ton of thickened poly.  Or do you cut down the coosa to fit inside the perimeter of the original exterior skin I left?  I've tried to find some videos of someone doing a transom this way with no luck.

I laid three additional layers of 1708 in the cutout area when I raised mine from a notched 25" transom to a full height to bring it flush with the existing skin. Then I did three full layers overlapping the bottom and sides - coosa - and three final layers on the inside. It's the same principle with yours except that your "notched area" is pretty much the entire back of the boat since it was all cut out. I would think that if you don't want to go that route then you could taper in a few layers to a foot or two to make it a smoother transition. Or maybe a combination of a taper plus one or two layers.

I can't imagine you'll want to do this a third time so the investment in the extra work and glass now may be worthwhile.

I Definitely don't want to do it again.  I was thinking about doing the same thing adding a few extra layers. thank you
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: RickK on December 21, 2021, 05:29:20 AM
Three layers is usually enough, especially if you use epoxy. 3 layers with poly is ok too. Then core, then 3 more layers.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on December 29, 2021, 10:07:31 AM
I am to the point were I have everything ground down with 36 grit, blocks are glued, and melamine is ready to mount.  I want to check the factory specs for the width of the transom at the top but I cant find the info.  Seems like it might be a little narrow at the top after the coosa was cut out but I dont have any Specs to compare.  If anyone has this boat will you measure the top width of you transom please and let me know the dimensions. thank you
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on December 29, 2021, 11:25:58 PM
I went ahead and started glassing the transom.  It was hard to tell if the back shape was perfect with the small waves going down the boat because the cap is off the boat id assume.  Having kids and not knowing how long I will get to work on the boat I bought laminating resin that is supposed to stay tacky where you can just start glassing the next layer with out sanding.  I laid one layer on the melamine and sandwiched to the the back of the boat using thickened poly with fibers.  Well I just checked and the glasswork i did is hard as a rock and not sticky at all. Damn I thought I was done sanding for at least a day.  Ive been thinking about it for hours and the only thing I can think is the wax I used on the melamine hardened the laminating resin.  Have any of yall had this happen?  I'm going to test a small amount tomorrow and see if it stay tacky or hardens.  Im going to try to lay all the other glass in one go. I have three full layers 4,8,12 and two more to go between the cut out, to build it some, to get a flatter surface for the coosa to bond to. But you never know with kids, weather, and life in general if I can do it in one go hence the laminating resin.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Ulysses485 on December 30, 2021, 12:43:30 AM
Although it might be laminating resin, that doesn’t necessarily mean it doesn’t have wax. The boatyard polyester resin from FGCI is considered a laminating resin (up to 1/8”) but typically contains wax and will cure tack free (their literature call it a non spec resin that may or may not contain wax). However, it’s hard to read the bottle you have but from what I find online it looks to be made without wax.

Regarding the layup, your best adhesion especially when going with poly is going to be wet on wet so you have a chemical bond and mechanical bond. It’s hard to tell from your precious post but did you layup a layer flat on a table of melamine and then bring that to the boat to bond to transom corners? Most I’ve seen set the melamine against transom and layup till the outer skin is done. Then bond the core into a bed of thickened resin to eliminate any voids or hard spots while also filling to create fillets so it’s close to ready for layup of structural tabbing to inner hullside/bottom.

Just my thoughts..
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on December 30, 2021, 08:52:21 AM
Although it might be laminating resin, that doesn’t necessarily mean it doesn’t have wax. The boatyard polyester resin from FGCI is considered a laminating resin (up to 1/8”) but typically contains wax and will cure tack free (their literature call it a non spec resin that may or may not contain wax). However, it’s hard to read the bottle you have but from what I find online it looks to be made without wax.

Regarding the layup, your best adhesion especially when going with poly is going to be wet on wet so you have a chemical bond and mechanical bond. It’s hard to tell from your precious post but did you layup a layer flat on a table of melamine and then bring that to the boat to bond to transom corners? Most I’ve seen set the melamine against transom and layup till the outer skin is done. Then bond the core into a bed of thickened resin to eliminate any voids or hard spots while also filling to create fillets so it’s close to ready for layup of structural tabbing to inner hullside/bottom.

Just my thoughts..

I did lay a layer of 1708 on the board and sandwiched it to the hull with thickened poly.  There was a 1/4 bevel tapering in that I wanted to fill.  I was trying to do the entire thing wet on wet but got interrupted.  I guess I was misunderstanding the entire laminating resin concept, I thought the resin was made to stay tacky at the surface so the next layer would form a chemical bond with the layer below.  I guess I'm going to rough up the coat with 36 grit , mount my layers to a board up top, and try to finish it out wet on wet.  I just hope it all bonds well to the one I already laid.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Ulysses485 on December 30, 2021, 09:12:46 AM
Conrad, is it safe to assume you are going to be adding additional full width layers of 1708 to the inside of the one you bonded from the inside of the transom? On second thought, I would personally not feel comfortable with the bonded layer adding much tensile strength to the transom. They should be laid up AND tied to the inner hullsides at the same time so the full length of glass is brought inside the transom sides for greater strength. I don’t know if that makes sense.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Conrad4784 on December 30, 2021, 09:56:58 AM
Conrad, is it safe to assume you are going to be adding additional full width layers of 1708 to the inside of the one you bonded from the inside of the transom? On second thought, I would personally not feel comfortable with the bonded layer adding much tensile strength to the transom. They should be laid up AND tied to the inner hullsides at the same time so the full length of glass is brought inside the transom sides for greater strength. I don’t know if that makes sense.

I am adding three full layers tabbing in from the inside against the melamine(layer of glass now) then coosa and another three layers.  the exterior layer was added to make sure I had a flat surface with out voids due to a 1/4 bevel inwards around the entire transom.  it should still have good strength 6 more layers of glass and coring goin in. I tried to show it in the previous post pictures.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Ulysses485 on December 30, 2021, 10:18:26 AM
You’ll have plenty of strength with three additional full layers to build the exterior skin. The only concern I would have would be stress cracking on the edge joint of where the first layer was bonded. There is a lot of stress on the transom from the outboard. Just my thoughts.
Title: Re: New project 1971 proline flatback. First decision engine bracket.
Post by: Tampa Bay Mike on December 31, 2021, 07:54:45 AM
Laminating resin will still harden but it's probably not fully cured. If you're not sure, give it a little wipe with some acetone and give it a few seconds to flash off and then touch it. If it's still tacky then you're good to go. If you do the same thing on something fully cured like the outside of the hull it will stay dry.
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