Should I departing from the designed plans?

I’m about to embark on a boat building project and looking for some advice on the modifications I plan to make to the design.
The boat I’m going to build is an Angus Rowboats Sailing Row Cruiser. It’s basically a large canoe style sculling rowboat with a small fore-cabin and fitted with outriggers to allow for a cat ketch sailing rig.

Lots of different sailing rigs have been used on these boats but the original plans use a ketch rig with a daggerboard towards the front of the boat, in the cabin.

To save costs I plan to use the sailing rigs I acquired from some boats decommissioned by my local sailing school. This would involve using two sails of the same size - which would mean moving the daggerboard aft to balance the sail plan.

Finding the hulls CLR and an appropriate offset to the sail plans’ CE is fraught with difficulty, so in place of a dagger board my preference is to use a pivoting leeboard as that will allow me to experiment with different positions along the hull for the foil. This will also simplify the build as I don’t need a daggerboard case.

The designer advises me to modify the aft sail and stick with the original plans. However, I’m doing this on a budget and don’t have access to a suitable sewing machine or sail maker. I’d also be very unsure how to brief a sail maker on what I wanted done to the sail.

I’m very reluctant to disregard the designer’s advice but I can’t help thinking that my option is the easiest to build and also offers scope to tune the rig to get it just right. Any slight performance hit to using a leeboard in place of a daggerboard would be of no consequence to me.

Does this sound sensible?

In case it’s of interest, the original plans call for the use of a set of Bic O’pen sails, the for’d sail being 48 sq ft and the aft sail being 30 sq ft. These sails cannot be reefed!

I plan to use the sails from a Laser Funboat. These sails are 51.67 sq ft each, sleeved around the mast and designed to be reefed by rotating around the mast. The designer has said that the original plans have modest sail area and this extra 32% of sail area should be manageable by the boat.

 

The gunwhales are probably not designed to take the load of a leeboard and you can't fit a crossbar reinforcement because it would interfere with the rowing station.
One solution would be to find an existing RowCruiser fit your rig to it and use a clamped on leeboard to establish the desired position in light conditions. Then design the proper hull reinforcement for that specific place.

The better solution is to build as per plans and just reef the sails appropriately when going upwind. The beauty of around mast rolling sails is that they allow continuous reefing, you can easily reduce to the exact needed size. To give you a head start do a little measuring on land and mark the 48sqft and 30sqft reefed size on the sails using some colored masking tape as reference then go out and fine tune. When satisfied apply permanent markers to the reefing line or sails.
Downwind you can use the entire area, just like flying a spinnaker.

 

I know the boat and the designer, don't deviate from his advice.
Talk to a local sailmaker, they will understand what you're talking about.
Better yet, have them talk with Colin directly.

 

Hi ColinSW, second hand domestic sewing machines from the 1970's and 1980's are tough, and strong enough for your sized sails. Check out garage sales and market places. All you need is a good wide zigzag, and rolls of polyester thread, some practices on any scrap material, and some patience. An un-picker may be needed. I recently made a good sail with a plain old domestic Singer machine, from scratch. Some spare sharp needles for insurance, and a good service beforehand - lubricating the internals, and don't try to race over everything flat out. Read up a bit about sail making beforehand, or just look at how a professionally made one was done, and copy the methods. Even an average job will look OK once used and stretched out a bit. With your own machine you can make repairs and alterations at your leisure for free. Off cuts make good gussets, reefing point reinforcements, and repair patches. It's not rocket science, until you try the more technical sail materials and aim for specific shapes. Once you have made something you like, you can take it to a sail maker, for them to make a professional copy, and incorporate extras, like leech lines, reefing points, see through panels, etc. A bit of floor space is very helpful for marking it up, and don't forget to allow for hems, folds, gussets, bolt ropes, eyelets, and whatever else. Make a mock up out of a bed sheet to practice, if unsure. See my posts a few months ago making a small balanced lug rig. I think called :'Jack Holt Heron re-imagined Part 5', or something like that.

 

A needle and a palm is all you need to modify a sail. They are not as expensive as a sewing machine and a lot more zen.

 

Not only no but hell no!
You always, no matter the device, modify the least expensive, easiest to change part.