Building a Corsair CR13

[Jaysen]

Yes... the increase in the lofted weight by lifting a shortened boom is much less than you add by lifting a full boom and then whatever you will do the trimmed sail top. The CE changes is the real danger though as that will require you to make changes to the CB. The new plan ... just lift the boom, trip the sail, shorten the boom. done.

[Brocky]

Yes my consulting engineer (youngest son) agrees completely with you. Thank you very much for your advice and wisdom, I really value having people like yourself and VT_Jeff to call on.

Ian

[Jaysen]

I’ve been smacked enough to need the helmet. Experience is the source of wisdom.

And wives. I was instructed to add wives.

[Brocky]

I think a wise man listens to his wife. Actually my very non mechanical wife comes up with some really good ideas sometimes, so with the boat i run my ideas past her for her thoughts. She looks at problems from a different angle to me. I've done lots of measuring and I think my ideas will work, so I'll go out soon and buy the alloy for the spars and see how it goes.

I notice most people that race small boats over here wear helmets, so if you are pushing it, its probably a good idea.

[Jaysen]

If you're going to race competitively a helmet will be required. If you are just "club racing" likely not, but encourage. Every week, someone got hit (or hit) something. Broken toes, fingers. Cut heads, arms, legs. And this was for pride not money. If you don't like medical bills... stay away from sailboat racing. Even as crew.

Just saying.

I'm lucky, I was dumb before I started racing so no one noticed results of repeated impacts to the cranium.

[Brocky]

Ah, I think you are selling yourself a bit short there. You seem to have lots of smarts when it comes to the technical parts of boat building and sailing.

As to the dangers of sailing, at the beginning of the year we had the annual Sydney to Hobart blue water yacht race with up to 100ft boats. They had pretty lively weather and 2 blokes were killed. One copped the boom to the back of his head, and the other got hit by the main sheet or block and went face first into a winch - ouch. So yes, something to consider alright.

[Jaysen]

Sydney to Hobart blue water yacht race

That's not "friendly neighborhood shenanigans" there. Typically trained crews. To me that's like driving race cars. You'r probably going to be fine. But then again... everyone goes to a demo derby and sometimes a race happens.

[Brocky]

Yes, put any 2 sailors together and you can guarantee they will see who is faster.

Actually, I will run some other ideas past you to see what you think. I have some time on my hands as I am recovering from hand surgery so cannot work on the boat, hence the investigation of masts and sails. I have not made any provision for oars for when there is no wind, so am thinking of an electric motor, specifically a trolling motor. I've been looking at Minn Kota and Watersnake brands with about 30 to 40 lbs thrust. Do you think they will push the boat along at normal sailing speed of about 3-4 kts? As to shaft length, is it correct that the prop should be about 12ins below the water? All up weight of the boat with load will probably be no more than 600 lbs.

[Jaysen]

I'd expect so. But I need to look at the plans for that boat. My overbuild v12 is a heavy pig at 150lbs. Which ever one you get, get an adjustable depth (on the fly) type mount so you can vary the depth of the prop. I find that unless I pull the mast I tend to need a lower point of thrust if I'm heading into the wind.

That said, I use oars almost exclusively. Just easier for me since so much of what I'm doing (fishing and napping) doesn't require a lot of power or speed.

[Brocky]

I'll mainly use the motor for getting in and out of landings, and getting home when there is no wind. Our area is not noted for high winds, so calm water is common especially on dams surrounded by mountains. My boat is 150lbs design weight already, and I have added a rotating centreboard as well as extra strengthening in the bow and deck areas, so it's certainly more than that, so will probably go for the higher thrust.
Both those brands are able to change the height on the water as well as the vertical angle and rotation drag. There is another brand I'm looking at, Newport, which I believe is made in the US that seems ok too.