Gilgo Gunboat - a Sunfish conversion

[Steve Sanford]

All~

In response to Joe Daly's inquiry, I have expanded the post on my own website to include 52 images of the conversion process. So here is a lighter presentation. For the complete blow-by-blow, go to "How I Do It" tab:

http://stevenjaysanford.com/sunfish-to-gunning-boat/


Here are the sketches I started with. Exact dimensions and construction details commonly change as I get to work.

I squared up my markings by using the transom as my baseline.

My side decks wound up at 10.5 inches - and I made this jig to follow the curve of the gunwales.

I used my skilsaw to do most of the cutting.

Then I removed all of the soggy foam floatation and the extraneous pieces of "framing".

I leveled up the hull in the shop with chocks screwed into the horses.

I used some clear treated SYP for the purlins - and ran them about 8 or 10 inches longer than the cockpit ends to avoid creating hard spots in the deck. They are fastened with 3M 5200 and SS panhead screws. The keel has been filled with insulation spray foam and will get covered with 'glass later on.

The fore and aft bulkheads are 1/2-inch AC plywood. They are 'glassed in along sides and bottom - but set in 5200 along their top edges.

Coamings are screwed into purlins and bulkheads - set in 5200, of course.

Backrest doubles as rowing seat - about 4 inches up off the floorboards.

It is held in place by a permanent chock on the floorboard.

The strut that holds the dodger/cowling up is tied to the bulkhead so it cannot be lost. The oars stow as planned in the bulkheads.

Lap cover is held at its foot by Common Sense fasteners - and at its upper end by shock cord over thumb cleats - so it "gives" when you sit up to shoot.

Oarlock stanchions are secured with galvanized carriage bolts - through backers made of half-inch ply and a bevel piece so that the washers and nuts land on a square surface.

Wooden (SYP) fairlead keeps the stern anchor line in place.

Here's the Gilgo Gunboat ready-to-hunt - on the Hemlock Swamp right here at Pencil Brook Farm.

And on the salt waters of Great South Bay.

All the best,

SJS

 

[Joe Daly]

Nice .... Too simple. I bet it glides with little effort.

 

[Gerald N]

Hi Steve,

Thanks for the post and sparking an interest. I wonder if jack plate could be added to the transom for a small motor for light thrust and not planning.

Chris

 

[Shawn Linn]

Boy that looks familiar, really nice to see the progression from start to finish. What length oars do you use in yours? I have progressed passed the fiberglass work and after some curing will be painting with FME. Now I just have to make a floor and add some oarlocks and cleats. I keep looking at the rope on the cutoff section and thinking I should put it on the shortened stern, or repaint the sunfish stripes on the bow.

 

[Steve Sanford]

Chris~

I'm sure that could work - but you might want remote steering - rope-and-tiller - so you could sit fsar enough forward to maintain the right trim (i.e., avoid squatting).

SJS

 

[Steve Sanford]

Shawn~

I used 6-foot oars - a pretty fair compromise between propulsion and stowability.

All the best,

SJS

 

[Shawn Linn]

That will work for me I have 71' between the supports. maybe I can find some 6'3" oars...

 

[Steve Sanford]

Shawn~

Oars usually come in 6 inch increments - so maybe you can find some a 6'6" pair.

All the best,

SJS

 

[fred slyfield]

Steve, Very neat boat you have there!!


Fred

 

[Cheech Kehoe]

That looks great. Thanks for sharing the step by step!

 

[CAnderson]

Steve-

I really appreciate you organizing all of those photos right here on the DB page. I know we have spoken of this build in the past and you were kind enough to send me your plans. I am still looking forward to building two of these for my son and I. We will get there soon enough.

I might have to get some good Jersey mud in Shawn's this year before we build ours.

Chad A

 

[rich scheffer]

Did somebody say Gilgo? Back in the summer of 62 I got my first surfboard, spent the majority of the next few summers surfing Gilgo Beach. What a great time that was! Rich

 

[TimJ]

Steve that is a nicely done photo essay. Thanks for posting it. Some day I'll find a sunfish around here that someone doesn't want a crazy amount for.

Tim

 

[Steve Sanford]

Rich~

The owner of this vessel lives right at Gilgo - and is probably surfing right this moment!

All the best,

SJS

 

[Pete Meyer jr]

Steve,
I posed this question on your site, but figured id post here to open it up to others.

I have in my possession what I thought to be a Sunfish. It was given to me by the Captain of a tug boat I worked on. He actually found it in Barnegat bay.
The boat is actually a ?Marburg 14? made in Florida. Possibly in the seventies. Not much info to be found on the net, but its almost identical to a sunfish.
I plan on making a conversion similar to yours with a few tweaks. I plan on splitting the stern to move a motor mount closer to the cockpit for one.
I guess it would look like two flotation pods attached to the transom.
The big question we have though is what size outboard to use.
At approx 14 ?, weighing anywhere from 120-150lbs no cargo or crew, im not sure how many horses we need.
Do you have any thoughts on the matter?
A displacement hull, a possible 500lb loaded weight, gunning on the south shore bays. Currents and wind can definitely be a concern here.

 

[Steve Sanford]

Good morning, Pete~


I look forward to seeing your project unfold. I would suggest you take a look through the conversion done by Curt Constance:


http://www.duckboats.net/cgi-bin/forum/gforum.cgi?post=335039;do=post_view;search_string=sunfish#p335039


There are probably other conversions right here on the site that you can review - just search on "Sunfish".



If I were going to convert one for power, I would be tempted to simply shorten the length by lopping off some of her stern and installing a new transom + motor board. I think that's what Curt did. A notched stern is a fine choice where you have lots of beam aft - but Sunfishes, of course, taper down pretty quickly. Regardless of the outboard you use, you will want a tiller extension.


I am glad you recognize that the hull is essentially a displacement hull. Although they can plane under sail, they would behave like a displacement hull under power. So, you are pushing the boat through the water - not getting up on top of the water. One good feature is that these hulls have plenty of rocker - so the nose should come up once you apply some power - and you will not be poking through head seas.


I think anything between 6 and 9.9 horses will meet your needs. A lighter engine will make a big difference on trim. As you know, the South Shore makes us run in shallow drive to make it across the big flats at times. So, the less weight aft the better.


I stowed my decoys in bags - either in the cockpit or lashed down on the foredeck. When the water got skinny, the decoys went forward - and I stood as far forward as I could and still hold the tiller. (And - if I let the tide run all the way out and got stranded - I set the outboard on the foredeck, too, and pushed the boat out over the mud or sand 'til she would once again float.)



View attachment Thatch I Sneakbox 1.jpg



Hope this helps!


SJS

 

[Pete Meyer jr]

Thanks Steve, great information to get me going in the right direction. There are definitely a few things to ponder.

I will check out Curt's conversion for sure.

this project gives me something to look forward to for when the season ends.