At last a build thread: CR16 skiff

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TomW1
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Re: At last a build thread: CR16 skiff

Post by TomW1 »

CR I think I have everything I need. I will use 1050 for your fishing weight we always guess low. :lol: and 1500 for your cabin trip. That is only 450 lbs and should be covered by your PPI lowering your draft by less than 2" just equalize the weight. You will probably be fine with the same prop, but I will check.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

cracked_ribs
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Re: At last a build thread: CR16 skiff

Post by cracked_ribs »

Well I'm certainly very interested to hear what you advise - thanks for the direction not just for me but for the countless forumites you've crunched these numbers for!
I designed my own boat. This is the build thread:

viewtopic.php?f=12&t=65349

TomW1
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Re: At last a build thread: CR16 skiff

Post by TomW1 »

CR finished the other members numbers and will work on yours tomorrow. What is your current prop size? Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

cracked_ribs
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Re: At last a build thread: CR16 skiff

Post by cracked_ribs »

Thanks man!

Current prop is a factory 9.25x11 identical to this guy:

https://www.boatpropellerwarehouse.com/ ... ler-763584
I designed my own boat. This is the build thread:

viewtopic.php?f=12&t=65349

TomW1
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Re: At last a build thread: CR16 skiff

Post by TomW1 »

CR just finished the calcs for your prop. They spit out a little larger prop than you have on now. The options are 10.25 x 12 or 9.75 x13. Your top speed will be in the low 30's. Of course this all depends on your weight of 1050lbs being accurate. For going to the cabin the 10.25 x 12 would be the better choice, iit will push you along fine with just a lower top end but right in the middle of the rpm range. Both will give you a pretty good hole shot at 1050lbs. Let me know if you have any questions.

Love the pictures of your kid, keep them coming.

Regards, Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

cracked_ribs
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Re: At last a build thread: CR16 skiff

Post by cracked_ribs »

Thanks very much! That's a big prop!

These motors won't fit anything over 9.25" diameter to the best of my knowledge; I'm not sure if anyone makes anything larger for this hub - is there a particular prop you know of built for it that matches the numbers you describe? I don't think I've run across anything like that but you probably have more knowledge of who makes what prop than I do.
I designed my own boat. This is the build thread:

viewtopic.php?f=12&t=65349

cracked_ribs
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Re: At last a build thread: CR16 skiff

Post by cracked_ribs »

This is a 9" diameter backup prop I have on the bottom end from the wrecked Johnson...centreline to cav plate is around 4 7/8", I believe. Could be a full five but hard to tell as it sits just at the moment. But much over a 9.25" prop would get sketchy in a hurry, I think.

Image

I know I could go up in pitch in theory...but is there enough area on the little prop to grip the water? That I'm really not sure about. I've seen 9.25x12s out there, but I wasn't sure if I'd have issues with the prop slipping from lack of contact with the water if I tried to get any more aggressive than 11 pitch.

Really makes me wish there was a 4-blade for these in 9.25x12. Again no numbers run on my end, I'm working purely on intuition from messing around with stuff. But I think that'd be a pretty good rig, if it existed.
I designed my own boat. This is the build thread:

viewtopic.php?f=12&t=65349

TomW1
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Re: At last a build thread: CR16 skiff

Post by TomW1 »

Let me look around a 9.5 looks like the max. Would not want to go over that for sure. These older motors are harder to prop than the newer ones. They did not give as much space for the prop and I forgot that.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Re: At last a build thread: CR16 skiff

Post by cracked_ribs »

No worries! Thanks for the effort you're putting in on my behalf here - this thing has been fairly difficult to source parts for accurately. The Evinrude 25 at least shows up in parts catalogues. But even so, very few prop varieties as far as I have seen.

Thanks though, it's really interesting to see the numbers you're generating.
I designed my own boat. This is the build thread:

viewtopic.php?f=12&t=65349

TomW1
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Re: At last a build thread: CR16 skiff

Post by TomW1 »

CR found two with a 9.25 and a larger 12" pitch. First is a Michigan Match Prop #012030. The second is a Johnson Prop #703590. These will do you fine and give you a better top end and a better mid-range. To me the Michigan Match is the better prop, but I have a prejudice against factory props. They just want to sell you a prop and do not do the research and development to make a good prop. Especially in aluminum. If you want a 4 blade prop I can get you one in SS, this is from the same company I recommend to all my other people that I work up their numbers for. With the PowerTech 4 blade I would recommend a 9.25 x 11 SWA 4 See here https://www.ptprop.com/a-class-propellers1.html They ship world wide and may have a dealer in Vancouver. They do near in Port Coquitlam, Poco Marine Ltd. phone # 604-464-8773 I have no idea what a small SS would cost but the larger ones are over $300. I highly recommend SS 4 blade they last longer help in steering and help in rougher water steering. You will need to check the number of splines as it doesn't say in the information I gave you.

Well hope this helps you. Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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