Designing/ building a modified Chugger

[matt167]

I was restoring my grandfathers 1963 Custom Craft Sea ray that he bought new in 1963/4ish and used as a ski boat, but the building it was in collapsed over one winter and destroyed it since the cap was off it but being stored on a frame overtop of it. I saved pretty much all of the cap, dash and the big fins to use on a tribute boat.

What I plan on building is a very heavily modified Lewis Boat Works Chugger design where I can place the original padded dash in the cabin, the original windshield ( plexiglass bubble type ) on the roof, and use the rear half of the cap/ fins and splashwell section from the original boat in the open deck portion. It will end up in the 16' range and somewhere in the 60" beam as the dash has to have a 60" structure to attach to side to side.

The variation from the original is of course the size, but I will also be using the original Custom Craft lounger seats and a forward/ remote control setup which will be on the rear cabin wall. Powered by a brand new 20-25hp 4 stroke which is over the design power tho not by a ton. I just want to be able to get out of a storm should one come up. It will never pull a skiier but an overnight lake/ canal boat. I would like to get it up out of the water/ plane if I need it to. 20mph would make me happy

I also want to add a full stringer/ knee system/ deck to the boat. I just need to make sure the finished product will float correctly and not capsize. As far as material. I'm thinking fiberglass skinned plywood. I can get ABX 3/8" douglas fir from one supplier for like $40/ sheet but another supplier can get SYP ABX for like $25 a sheet, and I think it just might be good enough for this boat. the boat roof and rear cabin wall will be 1/4" material with some light framing. no need for extra weight there

 

[Blueknarr]

As far as material. I'm thinking fiberglass skinned plywood. I can get ABX 3/8" douglas fir from one supplier for like $40/ sheet but another supplier can get SYP ABX for like $25 a sheet, and I think it just might be good enough for this boat. the boat roof and rear cabin wall will be 1/4" material

Welcome to the forum.

What a tragedy.

CDX (true exterior not "exposure 1") is barely suitable for hull construction.
SYP and ABX would never be applied together. The "A" and "B" are surface appearance ratings. SYP has no appearance rating as that it is intended to always be covered by roofing shingles. SYP has no place on hull construction. AAX or ABX would be a better choice than CDX.

Someone always climbs up onto roofs. They would lickly fall thru one made from 1/4 plywood

Good luck. I wish your tribute is successful

 

[matt167]

I would never use CDX.
I'm a little confused, as the supplier has a listing for "SYP A/B UL" sanded plywood which they say is ABX SYP and in the item description in their pdf listing it does say for interior/ exterior uses. I didn't understand it at first.. I must say that I have not bought any plywood yet and put a post here to make sure it's right before I do. If I have to go with the other supplier of 3/8" DF ABX I will, they are just kind of hard to deal with and it's a special order for 3/8". I could just use 3/8" for everything

 

[Blueknarr]

Sorry I brain farted and thought you meant CDX. Glad you're considering ABX. Again beware of ?exposure 1" vs "exterior".

The APA, American Plywood Association's web site doesn't have "SYP" in their data base. Putnam Lumber lists SYP as:
SYP Sheathing Plywood
Putnam Lumber distributes sheathing by the bundle and by the truckload. Sheathing plywood is an economical choice for use in structural applications, such as a roof, floor, or wall. Rated Sheathing has designated Span Ratings for use in load-carrying applications. Rated Sheathing is graded for strength properties and is not graded for appearance since it is generally not exposed in final use. CDX has the same load-carrying Span Ratings, but calls for a C grade face veneer or better. Sheathing can be ordered both untreated or pressure treated for protection against wood destroying organisms.

Sorry if I added confusion

 

[matt167]

Yeah, I'll just get the ABX doug fir from the other supplier and make sure it's true exterior.. I don't want to use a product that I don't exactly know what is. If SYP plywood isn't in the books as being face graded then I'm not sure what this stuff is. It's sanded plywood and is pretty nice but a boat isn't exactly a bookshelf

what about going to 1/2"? they carry it in stock

 

[Blueknarr]

What does the Lewis Boat Works specify for their "Chugger" design?

Without seeing the design, No one can advise plywood thickness. Increasing thickness is usually safer than reducing it. Will make hull heavier thus reducing payload. Thicker sheets Wil also be more difficult or impossible to flex into desired hull shape.

It is advisable to boil test a sample of the plywood before committing to it.

 

[Blueknarr]

The Anglefire website recommends 1/2 inch for bottom and 3/8 for topside. Allover 1/2 would acceptably avoid special ordering.

 

[matt167]

He advises 3/8" for all but the bottom, which says 1/2" for anything over 12'. I'm going to extend the bow curve so the bow does not have the flat section. I guess he was an active member here before his passing
Chugger http://www.angelfire.com/ego/lewisboatworks/html/Chugdes_a.htm

we posted at same time

 

[Blueknarr]

The designer knows best. Follow his instructions.