Lengthening Chugger.


I have come up with two different ways the lengthen Chugger. One is quite easy but will cause the boat’s proportions to change, perhaps making it look a little (more?) odd. The other involves stretching it somewhat proportionally, so keeping the intrinsic charm of the boat. Neither of the methods takes into account narrowing the bows, which is another document. Additional length of material will be needed to compensate for the length lost to the curves when narrowing.


Method One: 
	The first method is simple. Add X amount to the areas you want. If you want to lengthen the Cockpit , add1/2/3/4 ft aft of the circle cutout. Same with Cabin length, add 1/2/3/4 ft to the cabin. The only problem I see here is that the shape of Chugger will be changed disproportionately, and may look either stubby (er) on the ends or pregnant (lengthening the Cabin only) or like it has too long of a tail (by lengthening  the cockpit only) . I am not discounting this method and it will work fine for anyone who desires to use it and likes the look it will produce.


Method Two:
	On the other hand, if you want to stretch Chugger proportionately, I have worked out a method using a ratio of 1:3. How this is applied is best described by an example. If I were to add 2ft to the length of Chugger, the 2ft would be broken down into: 3in for the deck, 1ft for the cabin and 9in for the cockpit. How did I get these numbers? I started with the cabin. Using the 1:3 ratio and adding 1 ft to the Cabin, I would apply 3in to the front Deck length, and 9 in to the main Cabin. Adding the other ft to the Cockpit would mean adding 3in to the Cabin (thus 9”+3”=1ft) and 9in to the Cockpit (the 1:3 ratio). The beauty of the system is that 1:3 can be applied anywhere. Say I wanted to lengthen the Cockpit by a foot. It would actually be lengthened 9in, but the other 3in could be applied  to either the deck or the main Cabin and the boat would still be relatively proportionate when viewed from the side. Same with adding 1 ft to the Cabin: 3in to the Deck and 9in to the main Cabin. By adding the 3in to the Deck the additional length of the cabin blends into the design easier. For a full stretch to (approx) 16 ft, the deck would get 6”, the Cabin 2ft and the Cockpit 18”. It would still look like Chugger, though slightly leaner and meaner (hah, meaner like a puppy!). 

So here are some numbers to go by.

Adding length    Where you want it      Where it goes                                       

1 ft             Cabin                  3” to the Deck and 9” to the Cabin
1 ft		 Cockpit	        3” to Cabin or Deck and 9” to Cockpit
1.5 ft           All over	        3” to Deck, 9” to Cabin and 6” to Cockpit
2 ft		 All over	        3” to Deck, 12” to Cabin and 9” to Cockpit
2 ft (21”)	 Cabin		        3” to the Deck and 18” to the Cabin (adding 6” to  
                                        the deck just seemed like too much)
2 ft or (21”)    Cockpit	        3” to Deck or 6” to Cabin and 18” to Cockpit
3 ft             Overall                4” to Deck, 19” to Cabin and 13” to Cockpit  
4 ft 	 	 Overall		6” to Deck, 24” to Cabin and 18” to Cockpit   
Optionals:
4 ft             Overall            	6” to Deck, 18” to Cabin and 24” to Cockpit 
4 ft		 Overall		4” to Deck, 24” to Cabin and 20” to Cockpit 
4 ft		 Overall		4” to Deck, 20” to Cabin and 24” to Cockpit          

As you can see, you can play with these numbers after applying the ratio and also stick an un-ratioed foot in somewhere too, if you want.  Remember,  These are guidelines and can be adjusted somewhat. Moving 6” between Cabin and Cockpit would not change the lines very drastically, though changing the deck length by more than 6” would.  

The Front Curve:
	With either of the above methods the curve of the bottom should be eased in proportion to the lengthening, and for the additional scantlings (materials) required for the longer boats. The ratio for lengthening the curve is to add 4in for every foot of length. This means that starting with the 3ft measurement for a 12ft Chugger, measure back from the front, an additional 4in per ft of length before drawing the curve.   

When lengthening the boat, Remember that the butt blocks will not end up in the same places and you will need to add additional framing for the Cabin bulkhead and also go with heavier framing materials when and where needed. 1x2s will need to be replaced with 2x2s with the exception of when bending is needed. A few 2x4s may be needed in a 16ft version, depending on your anticipated usage. If you want to climb on the roof, you will want to frame it heavier to support weight. Remember though, on the water with the weight so high, you may get dumped if you are walking on the roof. I DO NOT RECOMMEND moving around on the roof unless the bottom is on solid ground!!!

Once you hit 14ft or longer, I recommend that you switch the bottom ply to ½” and the sides 3/8” up to 16ft. For a true 16ft boat, you will have to Scarf or Butt twice for the bottom and if narrowing the bows, for the sides also. I would make the additional joints at the ½ (or so) and 2/3 areas of the length of the boat. This is for two reasons. First, going half the length from front allows you to bend the ply without having a joint in the bend, and putting the second joint at 2/3s from the front will keep it towards the more heavily framed areas and reduce the stress to the joint, as opposed to having it right near the rear transom. Using butt blocks will enhance the framing too, but Fiberglass joints will work too and allow you to place the framing where ever needed. 

If you wish to continue the boat past 16 ft,  I’ll try to help but  you might be better served looking for a different design.