GF16 In The PSL

[Cracker Larry]

The last 3 or 4 feet are what's most important, that's what will be in the water when planing. !/4" of rocker in 8' is insignificant.

[Noles309]

Thanks CL. My concern was its all in the last 20" of the bottom.

[cedarock]

I pop in from time to time to see how my fellow boat building friends are doing and tend to follow boat building threads about boats that I am familiar with a little more often. When I saw this thread about the rocker, I sent Gary a PM about my experience with my gf14. I advised not to let the rocker go and thought about it and think that it should be shared for everyone to ponder and to help Gary and future builders come to the right conclusion.

I checked the bottom of my boat once while building and thought that it was flat from the mid seat back, which is what I had read in threads dating way back on the gfs. I launched with an old mariner 15 and was quite happy. It would push the boat 23-24 mph by myself and would plane okay with my wife and small dogs. Later, My brother and I took it out to the flounder hole and he weighs a touch more than Maggie! The boat really struggled to get on plane with that extra weight up front. I also noticed that the bow was riding higher than I thought it should and it would porpoise really bad by myself. I was okay for a while but about six months went by and I started to question what was going on. I then checked the bottom closely and found pretty much the exact rocker as is in this thread. Last 20 inches or so had 1/4 inch of rocker. My thoughts were that the boat was trying to run on that 20 inches. By adding weight, the motor struggled to lift the bow to run on that planning surface. Thinking about how to correct my mistake...... I decided to turn it over and take out the rocker. Luckily, I used graphite on the bottom and up the sides a bit. I taped the paint and sanded the graphite down some. I glued a 1/4 piece of ply to take half of the rocker out, cutting around the runners. I shaped it down with a grinder to about 1/8 inch thick toward the bow and used biaxal strips at varied widths to build up and take out the rest of the 10" or so of the rocker. I covered the ply and the biaxal strips with a full piece of biaxal. And then one more piece to cover the entire patch and around the sides a little. Then a new fillet along the runners and taped them again to tie it all together. Faired and rolled some graphite on it all.

I noticed a difference right away. The boat would run with a lower bow at 27 mph by myself with the same motor. No problem planing with two and porpoising was all but gone while running solo. I don't know if my repair was the best way but it has worked well for a couple of years and if it fails (don't think it will), a gf16 will be in the future with no rocker in the last 20 inches. I am sure that more horsepower would have overcome my situation and I thought about getting a 25 before the repair. I did replace the mariner with a four stoke 15, due to dependability of the mariner, and it performs the same with the heavier motor. Does any of this make sense or am I just obsessive about getting the best performance possible!

[Cracker Larry]

Does any of this make sense or am I just obsessive about getting the best performance possible!

It makes sense to me

[Noles309]

Thanks Cedarock for taking the time to address this issue.

I'm a little perplexed about the lack of comments on this as well as some contradiction of advice given in past threads. Those threads were all consistent in that the recommendation was to fix the rocker. The GF boats should be flat from the mid-seat to the transom...Now, it was designed into the boat and the same amount of rocker as outlined in past threads is ok.

[Noles309]

Crickets... Not surprised

I'm fixing it btw pretty much like cedarock did. Iv'e read too many articles and threads on forums about mediocre performance and porpoising with rocker to leave it.

[Cracker Larry]

You have OCD like I do I really don't think 1/4" will make any difference, but if it worried me I would certainly fix it so I could sleep at night. It will be quick and easy to build it up flat.

[Noles309]

You have OCD like I do I really don't think 1/4" will make any difference, but if it worried me I would certainly fix it so I could sleep at night. It will be quick and easy to build it up flat.

You got the OCD part right for sure. I would just hate myself if I didn't fix it and then wasn't happy with the performance of the boat. I've strewed about it for a week now. Its a small setback I guess in the overall process.

[Cracker Larry]

I've strewed about it for a week now.

You could have fixed it in less time than you've been stewing Make her flat and get some sleep.

[Noles309]

Fixed it for the most part, I did it like Cedarock. I still need to tape over the runners to tie them into the repair and fair it in now...