And so it begins!

[JohnC]

I finally bought a 1977 Master Angler hull that I want to rebuild and will be getting started with a "hull-up" restoration. I work and I have kids so I expect some starts & stops along the way but hopefully I can do this without dragging things out too long.
The deck is off and the stringers are pretty uneven across the top (thanks WaveWalker for pointing out that a shovel handle is not a suitable straight edge!). I also have some wet foam in the box stringers and I am going to attempt to remove it by cutting out the tops of the stringers and getting everything clean and dry inside. I am planning to raise the stringers slightly to even everything out and to get a final deck height that is close to 5" above the chine at the transom. I read a post by Denny that his waterline is about 4" over the chine at rest so I am guessing that my finished rig (375 lb. motor on a bracket) will be close to that.
I plan to core the transom with 2 layers of 3/4" Okoume plywood. It weighs the same as the Bluewater 26 but a lot less $$. I am planning on 1" NidaCore for the deck. It is relatively inexpensive and really light weight. I was planning to lay it up with two layers of 1708 on top and one on bottom. I am not sure about the core or the layup yet but I want light weight and stiff and this stuff seems to be that. My biggest concern is the right layup and properly planning all of the places for screw reinforcement under the deck since a screw into NidaCore is pretty useless.
There seems to be enough room for a Moeller 52-Gallon belly tank under the console but not sure until the stringers are raised and I can measure everything.
I value the experience of the people on this site and I hope you will let me know what you think!
"Without counsel plans fail, but with many advisers they succeed." (King Solomon)

[FAS]

looks like you have some work ahead of you, but you do have a plan,thats good.I do agree you will need to make sure the screws can have an indefinite bite where needed.either extra glass on a foam type core,or a solid bite on something that can be filled if there is a problem with a loose screw.Wanna hear more on this .....good point !

[Blue_Heron]

Originally Posted by JohnC

I finally bought a 1977 Master Angler hull that I want to rebuild and will be getting started with a "hull-up" restoration. I work and I have kids so I expect some starts & stops along the way but hopefully I can do this without dragging things out too long.

Estimate how long you think it will take and how much it will cost, then multiply both estimates by 4. Not trying to discourage you, just open your eyes. Look through some threads where the poster completed the project. Then check the date of the first post and the date of the last post. If you go into this with realistic expectations, you're much more likely to finish successfully.

Originally Posted by JohnC

I plan to core the transom with 2 layers of 3/4" Okoume plywood. It weighs the same as the Bluewater 26 but a lot less $$.

Hmmm. I haven't worked with Okoume, but it must be light if it weighs the same as Bluewater 26. Most plywoods are about twice as dense. If you go with wood core, I would suggest epoxy resin for the laminate. It has much better water resistance than polyester.

Originally Posted by JohnC

I am planning on 1" NidaCore for the deck. It is relatively inexpensive and really light weight. I was planning to lay it up with two layers of 1708 on top and one on bottom. I am not sure about the core or the layup yet but I want light weight and stiff and this stuff seems to be that.

I've considered NidaCore for a deck, but haven't used it yet. It's less expensive than structural foams, but at 5lbs/cf, it's not significantly lighter. Not sure why you would use 1". With proper laminate thickness, 1/2" is probably adequate for the span you're looking at.

I would rethink the laminate schedule you've described. One layer of 1708 is going to give you a laminate less than 1/16" thick. That's paper thin. Two layers will be between 1/16" and 1/8". You can probably get away with two layers of 1708 on the underside, but the top side needs to be impact and puncture resistant. If you drop your anchor on a deck with a 1/8" upper laminate and a honeycomb core, it's going to crack or puncture the laminate.

The best advise I can give is this; Any time you're thinking of doing something different from what the original builder did, ask yourself one simple question: Are there any production boat builders doing it this way? Just about every time I've had a "great new idea", it has turned out to be either not great or not new.

Good luck with your project. If you can stick with it to the end, it will be very rewarding.
Dave

[FLexpat]

1 layer of 1708 is between 0.044" and 0.052" thick depending on how good your resin/glass ratio is.

Here is the Original deck schedule for early ‘70s 23’ Sceptre; top to bottom (from Feb ’73 Boating, Boat Test #207)
1 layer 3/4 oz mat
2 layers of 1 ½ oz mat
1 layer 22 oz roving
1 layer of 1 ½ oz mat
3/8” end grain balsa
1 layer of 1 ½ oz mat
1 layer of 22 oz roving

The top skin was originally ~.195" (not counting gel coat) and the bottom skin was ~0.080" depending on r/g.
Most of what was in the top skin seems to have been for durability/damage resistance rather than in-plane tensile strength.

You might want to think about a bit more than 2 layers on top and 1 layer on bottom.

[FishStretcher]

What FLexpat said.

I think on the 25s, the top is closer to 1/4", plus gel coat.

What I think about wood:

http://www.classicseacraft.com/commu...ad.php?t=26048

I have a photo of a sectioned deck here:

http://www.classicseacraft.com/commu...8&postcount=63

I haven't used it in a boat personally, but a lot of airplane decks are honeycomb structure. I like the idea.

Originally Posted by FLexpat

1 layer of 1708 is between 0.044" and 0.052" thick depending on how good your resin/glass ratio is.

Here is the Original deck schedule for early ‘70s 23’ Sceptre; top to bottom (from Feb ’73 Boating, Boat Test #207)
1 layer 3/4 oz mat
2 layers of 1 ½ oz mat
1 layer 22 oz roving
1 layer of 1 ½ oz mat
3/8” end grain balsa
1 layer of 1 ½ oz mat
1 layer of 22 oz roving

The top skin was originally ~.195" (not counting gel coat) and the bottom skin was ~0.080" depending on r/g.
Most of what was in the top skin seems to have been for durability/damage resistance rather than in-plane tensile strength.

You might want to think about a bit more than 2 layers on top and 1 layer on bottom.

[JohnC]

Thanks for the suggestions!
Dave, I have not handled the Bluewater 26 but I have worked a little with the Okoume and AB Fir and there is a noticeable difference in weight as well as quality. I am going by the Bruynzeel Okoume 18mm specs when stating the weight. The literature says a 4 x 8 x 3/4 sheet is 52#. There are 2CF of plywood in a ¾” sheet so that makes it 26 lbs. per cubic ft. It’s very dry wood and I think it gets a little heavier if not stored dry but not a lot.
As far as the NidaCore for the deck I am not fixed on it, I have only seen test results and reviews, no first-hand experience. It seems to be more rigid than other products when laminated but also more difficult to work with – edges require filling or capping and almost no screw holding strength. I saw test data with 2 layers of 1708 top and one on bottom but I see that is not a practical layup. It sure is stiff though!
Flexpat, thanks for the layup schedule – that is great reference material.
Fishstretcher, I am not uncomfortable using wood but I definitely see the down side. There are plenty of old boats with good wood but they are all a screw hole away from trouble. I like the strength of wood/epoxy for a transom and I know how to attached stuff to it without letting water in. I’m still a little mixed on this one! Honestly part of it is the cost. The layup for the transom with Bluewater will cost more than I paid for the boat. I don't want to go cheap on my project but that stuff is pretty steep.

[shine]

You can use almost any core for the whole boat, but each one has is strengths/weakness and cost to account for..........

I plan to core the transom with 2 layers of 3/4" Okoume plywood.

I love Okoume, I used to be an imported of it, and sold an awful lot of it.... But I would not use it on a transom. It is less weight, yes, but it is also not as rot resistant and in a transom is really not going to save you much weight when you consider the amount of glass and putty. I could get it at the price from the mill in Africa and I went with plain fir on my SC rebuild.

As far as the NidaCore for the deck I am not fixed on it, I have only seen test results and reviews, no first-hand experience. It seems to be more rigid than other products when laminated but also more difficult to work with – edges require filling or capping and almost no screw holding strength.

that sums up Plastic Honeycomb well. Stiffness comes from thickness of core, so thicker is better. Very little weight difference in going up in core thickness but stiffness increases exponentially. Filling the edges is a pain, so I like to use this core in area where there are few holes

I saw test data with 2 layers of 1708 top and one on bottom but I see that is not a practical layup. It sure is stiff though!

One layer would be very strong, the constraint on the topside is puncture resistance - why you need more glass on topside

There are plenty of old boats with good wood but they are all a screw hole away from trouble. I like the strength of wood/epoxy for a transom and I know how to attached stuff to it without letting water in. I’m still a little mixed on this one! Honestly part of it is the cost.

I just cut out perfectly dry and solid stringers out of a 37 year old formula (next project boat) - if you use epoxy and the right techniques there is no reason plywood core cannot last "forever"

The layup for the transom with Bluewater will cost more than I paid for the boat. I don't want to go cheap on my project but that stuff is pretty steep.

If I were going to spend a little extra for that material, I would put it in the transom first - high compression strength and the transom gets a lot of holes below the water line

[JohnC]

Lots of good input here. I am likely going with Bluewater 26 or Corelite for the transom after all. I will post picks when I get into it. I will also do a layup for the deck that more closely matches the factory layup.
I would like to know why the stringers do not go all the way forward to the bow? I have looked at several rebuild threads and it seems that, even with level deck all the way forward, the stringers are not extended to the bow. Is there a reason for this that I am missing?
Also, the stringer height at the transom is usually raised. I imagine that that is to add strength to the transom to offset the weight of the motor/bracket but it seems unnecessary. My idea was to run the deck from the tip of the bow all the way back to the transom with a shelf to carry the edge of the deck glassed in all the way around. I will make a hole/hatch in the deck for bilge access so I'm not giving that up, just moving it forward a foot or so. If I raise the stringers at the transom I would have to cut the deck around it and re-think a few things I have planned for the transom (2 insulated boxes draining out the sides of the hull, keep one of the original ones and make another that extends across the motor well area to make a large fish box). Not a big deal but I need to plan properly.
Questions:
1) Why not extend the stringers forward to the bow? There will be no casting deck.
2) Do I need to raise the last foot or so of stringers to support the transom?

Thanks,

[Bushwacker]

Originally Posted by JohnC

. . .
Questions:
1) Why not extend the stringers forward to the bow? There will be no casting deck.
2) Do I need to raise the last foot or so of stringers to support the transom?

Thanks,

The 4 stock stringers in my Seafari go all the way to the bow, at least to the point where the bottom of the hull rises to the top of the stringers, where they just blend into the hull. I suspect that the hull deadrise from that location forward is high enough that the hull shape alone creates a lot of stiffness. However the Seafari bunks, or the casting platform in the CC models, also add additional stiffness, so increasing the thickness of the deck core forward of the stringers might not be a bad idea. As Joel mentioned, stiffness of a cored structure is proportional to thickness raised to 4th power, ie, a 2X increase in thickness will increase stiffness by 16X!

Regarding the transom/stringer joint, the original stock configuration was designed for twin engines of approximately 170 hp total, but if you're planning to add a bracket, which will tend to increase the leverage/bending moment of the motor on the transom, adding some gussets at the transom certainly can't hurt anything, especially if you're planning to hang a big heavy 200+ hp motor on it!

[JohnC]

Thanks Denny. I am not planning anything big & heavy on the back, I'm considering a 25" shaft 90 ETEC (330 lbs.) or 115 Merc 2.1 Liter (370 lbs.). Since a motor is a year or more away I am not really choosing at this time. I would also like to see some more reviews for the Merc after it’s been out in the market a while longer. I will also be putting a floatation bracket like yours on it. I think the load distribution of a bracket with platform will help carry the weight across the width of the transom rather than pulling down in the center only. I was planning to beef up the tabbing up the sides of the transom since that area does not affect my fish box plans and the swim platform would distribute some of the load to the edges. I may be making too much fuss about keeping the deck level all the way to the transom anyway. I will know more when I start building stuff and fitting it together.
Regarding motor weight, I had a chance to take a ride in a very nicely restored Potter 20 over the weekend. Great ride but also very stern heavy. The owner (not sure if he is a CSC member) put an aluminum bracket and a new 250 Optimax on the back (505 lbs.). The chine at the transom rides around 7” below the waterline at rest. The boat planes at around 20 MPH with the tabs all the way up and starts to fly straight and level at around 27-28 MPH with 20 gallons of gas and three fat guys on board (no tabs). I tried to level it with the trim tabs while running around 45 and it was a little scary how fast the whole world tilted sideways. I had to slow down to around 35 to safely adjust the tabs. This thing is a real rocket! Definitely not what I am looking for in a 20' Seacraft but it sure is fun to push the throttle forward and watch the world behind you get smaller and smaller. I think that tweeking the prop and motor height would make this a 55-60 MPH boat - just not with me on it!