Sunfish boat build

[gbftats]

Hi guys, im new to the forum and i thought id start by talk about the boat build my dad and I are working on and perhaps get some advice.

We had an old foam core sunfish knockoff that was de-laminating and completely water logged (believe it or not!). The boat measured 12' long and i wanna say 32" wide(?) at its largest point. So we cut the boat down the center and set it out under some black tarps for a week to dry out. The next step on the list is to widen the boat a 1' and lengthen it another 2' bringing it to a total of 14' long and just under 4' wide. Now we are trying to decide where the new mast position will sit with the geometry changed.

The hull is somewhat of a flat bottom design that we will be switching to more of a V bottom. The dagger board and rudder will be modeled after the laser for efficiency. Im in the process of ordering a sunfish racing practice sail which i hope will be adequate. After the many hours of micro ballooning, and sanding we will be adding aluminum plates, cleats, ect ect followed up with vacuum bag fiberglassing, prep 'n paint.

That is the general build give or take a few options. Any suggestions are welcome as it still is in some what of the planning stage!

Thanks.

 

[AQBill]

A picture is worth a thousand words. Send pictures - sounds like is could be a minifish or perhaps even a sailfish...

 

[Trueke]

Sounds like a lot! but the before post is right...

 

[Wayne]

We had an old foam core sunfish knockoff

• The next step on the list is to widen the boat a 1' and lengthen it another 2' bringing it to a total of 14' long and just under 4' wide.
  
• Now we are trying to decide where the new mast position will sit with the geometry changed.
  
• The hull is somewhat of a flat bottom design that we will be switching to more of a V bottom.
  
• The dagger board and rudder will be modeled after the laser for efficiency.

Any suggestions are welcome as it still is in some what of the planning stage!

Your boat’s hull bottom design sounds typical for beach boats. They are fairly flat-bottomed so they will plane (hydroplane) for speed.

Daggerboards and rudders have two key elements in their design, one is their hydrofoil cross-section for efficiency, the other is their surface area as part of the boat’s lateral resistance equation. Look around the internet for articles on Center of Effort and Center of Lateral Resistance. These may help you decide how the mast and fins should be placed in relation to one another and positioned on the hull.

Check to be sure your boat hull is constructed from fiberglass. Some foam-filled hulls were made from materials such as ABS or polyethylene. In those cases fiberglass repair materials would be incompatible and you’d need to look toward something like WEST’s G-Flex epoxy.

.

 

[gbftats]

thanks for the resources wayne! I will take pictures of the project monday when i head down the hill to work on it.