Performance Advice Please !!!!!

D

DC45

New member
I have read just about every thread on these forums over the past several weeks about Props, Trim-Tabs and hydrofoils. Only problem is; most people own CD22's and CD25's. I have a 2004 CD19 (angler) with a 2005 90HP Honda and run the coastal waters of Alaska and Prince William sound (in search of the Barn-Door Halibuts). I love my C-Dory to death, and I am a devoted fan of the boat. I have owned several different boats in my 42yrs of life, and by far this is the best one yet. I have only two dislikes about this boat. (1) The flat rear end makes the give a very very awkward side slide under certain sea conditions (almost scary in fact). The boat came equipped with dual Bennett Trim Tabs that help in rough water when running straight. I recently ordered a "Permatrim" hydrofoil, which from what I have read on these forums should help this sliding condition (I hope). (2) I would like a better speed from this boat (when seas permit). Now I understand that the C-dory was not built to be a "speed-racer" type boat, and I don't want to go 75 MPH and turn on a dime, but I would like to get maximum performance possible from what I do have. Can anyone recommend a PROP that would give me max performance for this boat, I have the stock Honda prop now, I hate to just start guessing what to buy, maybe someone has a CD19/Honda 90 combo who has found a good combo. 3 Blade or 4 Blade, Alum or Stainless or Composite, 15 pitch or 17 pitch or ???? Any advice would be Great...I know you guys are for the most part the experts on these boats..

Thank You

DC...
Quiet-N-Shy, Eagle River Alaska
http://www.arcticfusion.com
 
I don't have a 19ft but do have a 90 hp honda. I have owned a few different small boats in my time, 41 years, and have always felt that 4 bladed props are better. They give better performance at mid speed. for example my 19 ft starcarft with 70hp evenrude 2 stroke would plane at as little as 15 mph with the four blade but only 18 with the three blade. I also feel that 4 blades will hold a turn better then a three on the same hull. They also troll far smoother and slower then a three blade. I was not a true believer in the four blades until I tried them but would never go back to a three blade prop. You will have to differ the pitch and try different sizes until you find the best one for your combo. I was very impressed with the compprops on my other boats and for a will on my c-dory but at 22 ft and loaded heavy I think that the compprops are not strong enough. but for a 19 ft boat thats used as a day fisher that my susan has not loaded down then the compprop would be a good bet. hope this helps and does not just add a layer of confusion to your search.
 
It would help if we knew your WOT rpm and speed. It would also help if we knew how fast you were running the boat in various conditions currently.

We found on the 22 that we got over 30 mph with a 90. We had 3 props, mostly because of altitudes--13" 15" and 17". The Evinrude may have a slightly different gear ratio than the Honda, and the 19 being lighter, you may get by with a 19".

I wonder about the Permatrims. Generally they are used to get the bow down, to decrease planing speed and decrease cavitation. In following seas, one usually brings the trim tabs neutral or preferably up. The Permatrims will accentuate the outboard trim--but could be slightly adverse in following seas. Most of the recent posts on Permatrims have been on the TC 255 or other boats which didn't have trim tabs. I have so far only used similar fins (Dolfins) on smaller light boats. I didn't see any help in following seas.

The C Dory is very flat in the aft sections, and there is little to grip the water, but I have never felt that the boat is broaching--if you trim the bow down, it would bow steer and could give some of the problems. Bow up in following seas. The C Dory does do better at slower speeds (and does plane at lower speeds than most boats)--than at high speeds, even in following seas. We find that in heavy following seas, that use of the throttle is almost as important as steering.
 
thataway":16n4akm5 said:
The C Dory is very flat in the aft sections, and there is little to grip the water, but I have never felt that the boat is broaching--if you trim the bow down, it would bow steer and could give some of the problems.
Click to expand...

Indeed. Inadvertent overuse of the trim tabs can make the C-Dory positively scary and it can creep up on you. In my humble opinion trim tabs are a valuable asset but the skipper has a much narrower margin of error in changing conditions. What might feel right on a straight run suddenly turns to pucker time in an unexpected avoidance maneuver. The C-Dorys do love to stick their noses in the air and that seems to be where they're riding the safest.

Don
 
DC - I think you ought to check out the Propulse, adjustable pitch, composite props like the ones El and Bill use. It is four bladed and you can change the pitch for your use - lower pitch for heavy loads and trolling and higher pitch for speed. I am sure you know the best place to start is with a pitch that puts the engine in it's designed high rpm potential. You can, however, vary from that as best suits your needs.

As for the Permatrims, my understanding is that the downturned side edges help to hold the stern in position, even if the tabs themselves are not adjustd down. I think they'll slow the stern slide.

John
 
Thanks all for the insight, I should have the Permatrim plate in the next week or so, just have to wait until the 8 feet of snow my boat is buried in to get it installed and try it out, I'll post a informal report of the results.
 
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