must ski, It seems to me that a little up trim would fix the bow steer. I trim up to the mark at about 20 and use that setting for 20-25 and above. If I ever build another 18 (which I doubt), I think I will have a tank made that conforms to the shape of the bow and put it as far forward as possible. Then just use the fuel level for ballast if needed. jim
But on a 20 the V of the boat is alot longer and more of it is in the water. The wedge really stuffs the bow down and forces it to the right because the prop rotation is pushing the back of the boat to the left. It is really not needed on the 20's unless you have a true 20' factory single with the fuel tank in the rear. Even then the boat is long enough that unless you are pulling 10 people bow rise is negligible. The bow steering really scares people and that is why I don't use a wedge on our 20 footers. The natural instinct when starting is just to trim all the way in and with a wedge on a 20 that is too much.
I guess I am just used to trimming. When I had the Mirage Jaguar, I started with the trim all the way down, and as soon as I hit it I held the up trim to try to keep the bow from coming down. It would usually bounce once before I got enough up trim in it. Even then it was a better hole shot than starting with the trim out. At about 80 I had to trim back in a little to prevent a blow over. I just keep the boat in the proper trim for the situation. I have seen a lot of ballast in the multi engined boats and wonder if a wedge would help that situation if properly driven. You don't have to use it all. jim
78Hydrodyne: I can shed some light on what to expect, as I've got an 18' with a 225 Optimax. Running a 19 pitch Mirage prop and an 18 gallon bow tank, the boat does pretty well on full fuel. Below half tank, it gets light in the nose and with a heavy skiier it wants to porpoise, even with the trim nearly all the way down. With a 512 lb motor on the back, and the tow pole at the back, you can't really use all that power because it wants to pull the bow into the air when you try to pull a big load, such as several big guys on a deep water slalom start. Personally, I think the boat needs some balast weight up front. I understand the wedge conceptually, but continue to question whether it is better to add some weight up front or direct more thrust down in the "tuck." I undertand that more weight is generally bad. However, directing more thrust downward to push the stern up and the bow down also absorbs power - it has to. So it is a physics issue, and I can't answer it. Jim uses the wedge and likes it. He does a lot of slow stuff and it seems to work great for that. On the other hand, he has a fairly light engine back there. He's not trying to offset as much weight with the wedge as you will be. In all things boats, however, I usually defer to Jim, who probably knows more than just about anyone. I'll be curious to see how things work out. I've been trying to decide whether to put a wedge on or just try some weight up front this year. I have way more power than I really need for what I do so that weight would probably work well for me and would balance this boat - which definately needs some balance. Using more power, with more tuck, is one way to get the boat to sit down at low speeds and out of the hole. However, will this put more pressure on the transom than bow weight? Also, weight will do a great job of keeping the bow down, as you can prove to yourself in a small fishing boat very easily. Move someone from a middle seat to the bow and the boat picks up more speed very quickly. So is more weight necessarily a bad thing? Not sure. The ski teams use bow balast all the time. I haven't seen them use the wedge much, although most of them are running 20 footers now. I say go for it, and let me know how it works so I'll know whether to go that route! I will say this... if you are into Dyne Walking, and I'm not saying you should be, the bow weight will probably make it hard to do that in a single rig configuration. My boat will walk fairly easily with a light fuel tank, but is resistant to standing up when the tank has a good bit of fuel in it (not that I do that sort of thing... ) Markbano
RiverRat has run his 18 with and without a wedge and can tell you the difference. I believe he is using a 200HO which is a big block I think. Here is the thread where he talks about it a little: http://www.hydrodyners.com/forum/viewtopic.php?f=23&t=494&st=0&sk=t&sd=a&start=90 I don't think he is running ballast and the boat is used in the show. Maybe he will comment on that. My view is that even if the wedge will not eliminate the need for bow ballast, it will at least reduce the amount required. If I set my trim where it would be without the wedge the bow comes up when adding power. It then "falls over" when it reaches planing speed. With it full in, it just comes straight up and there is no "fall over". That is with no skier or just one skier. My motor only weighs 370. edit: And Mark, when you add weight to the boat it requires more engine power to get it on plane. It is not free. jim
For pulling big things, we usually pull straight from the transome so I don't think this will really be an issue for us. I have also installed cleats on the sides for things like barefoot lines so that really doesn't pull the nose of the boat up. The only thing that tends to be a problem is doubles and trios because the have to be on a release on the pylon. I think the wedge will be good enough to get it off the dock with out the nose rising. Here is a picture of the cleats.
Markbano - I don't think it's true that you can't use all the power with a 225 opti. Here is the identical boat from our team... These guys can all do a dock start behind this boat with the cleats and the nose doesn't budge.
I don't have a dyne but I do have two outboard ski boats. One I have installed a 3 degree wedge on and it has transformed the low and mid speed handling. In the other, the transom angle is already set at -19 which is about 5 more than almost anything else. So the wedge is built in to the transom. This boat is fitted with an E-TEC 225HO which has a -6 angle built in which is quite a bit more than most other motors (normal is about -3). Yes, that is a lot of negative trim but I like and use it all often. The negative allows me to get the level running AND have the fuel tank under the floor at the rear of the boat. That is an excellent place for it, out of the way, otherwise wasted space between the bearers. In this thread you can see a photo of my new boat with the -19 transom pulling 8 skiers from the deep from the pole. The photo was taken just as the skiers were about to come up - at peak load. viewtopic.php?f=18&t=818 My #1 boat has a fuel tank in the nose. I didn't like having to run it full all the time as it makes the wake bigger than necessary, increases drag (and thus must increase fuel consumption) and was just something I didn't like doing. I'd much rather trim down when I want to and trim up when I don't need that drag/downforce any more. I can understand Must skis comments about bow steer. I have felt it before on other boats, but not mine and you wouldn't want that. Must ski, does that issue only happen with a 5 degree wedge or also with a 2 or 3? Persoanlly I'm a huge fan of wedges and I recommend them to a lot of people. They are cheap, not that hard to fit and a lot better than some solutions like those fin things. I wonder what the 20 would be like with a rear tank and -3 of wedge??
Jim is correct. I started out with a 200 HO E-tec and no wedge. Then I tried with a wedge a few weeks later. I see no reason to remove it. It definitely helps reduce bow rise. I also see no need for additional ballast in the bow of an 18. I do, however, have to carry a few cheeseburgers around to entice some additional ballast known as a "second spotter" into the boat for some larger pulls from the dock. Just make sure you save at least one cheeseburger to get the ballast out of the boat (toss the cheeseburger on the dock) when you are ready for more barefooting, jumping, fun stuff, etc... I have not tried a wedge on either of our multi rigs, but have considered it. We do run about 150 lbs of sand in the bow of the twin and a little over 200 in the triple. The twin does have some bow steer if you aren't careful with the trim. The triple would probably flip over if you didn't trim up and used a good portion of the throttle. But, of course, why would you have an inexperienced driver that doesn't understand how to use a trim button driving a 20' boat with 525+ hp? Less weight in the boat = more power to pull people, more fuel efficiency, better handling.
Guys.... Great tech discussion. Lots of great experience and knowledge on this website. My knowledge is largely limited to rebuilding - I don't have a fraction of the driving experience of many of you and I have never driven for a ski team - so I appreciate all of the education. I'm sold. I'm going to order a wedge today and get it installed before I bring the boat up north. Jim - Am I going to need longer engine mount bolts?
