Tunnel Hull Design

[moparbarn]

my villain had them on it when i bought it a few years back, gene. grim had installed them for the original owner to help stop it from hopping in the straights. for me, it was always blowover happy until i removed them........runs great now. i think they added too much lift for my setup.

 

[Slideblues]

Ahh Yea, Tha lift thang.........Hmmmmmm,

Thanks Robin,

Gene

 

[RodneyPierce]

Mike, thanks for commenting here on the secondary ride pads!!! Much appreciated, and PERFECT explanation. I am also going to try a few things here this next year with tunnel design. Some may work, others may fail. But thats how a person learns!!

 

[David Moyle]

I agree, thanks very much Mike for a detailed and informative explanation!

 

[RonShaw]

I've seen Mikes 295 design in action that Dick runs in the B Stock class as well, and I will say it is one of the fastest B Stocks I have seen. One very important note on the use of secondary ride pads is how critical it is that all

straight edges on these pads must be PERFECTLY parallel with the existing inner and outer edges of the sponsons or they will either give you additional unwanted lift or work against you and can actually add unwanted drag!!!!!!!! Great explanation Mike!!!!!!!!

 

[lohring]

The comments on secondary ride pads is very interesting. The P spec boats we race started as nitro boats like the VS-1, Top Speed 3, and my modified wood Leecraft XTR-21. They all seem to be more prone to hooking and spinning out in the turns than the nitro boats. This can be held off with careful balancing, but the sponsons are probably a little overloaded. I might try a wider sponson with the secondary next season.

Lohring Miller

 

[LarryConrad]

I guess I can Kris. I just don't want it turning into an argument like it normally does when I post in a tunnel thread. These are my views and I have tested them.

First, I would like to discuss why you would, or would not need a secondary ridepad. As Larry Mentioned above, none of his current hulls have secondary pads. Probably a good reason for it. A typical tunnel design specifically built to carry the light load of a nitro setup would not necessarily need wide primary pads to begin with or large sponsons for that matter, so the overall benefit might be pretty low if you primary pad is narrow to begin with. One of those hulls Larry mentioned has a mild problem with extremely slick water conditions, it gets "sticky" on the water, and could probably benefit from a secondary pad, but slick conditions don't really exist to often in race water, so its not a big deal. It also happens to have the widest primary pad of the group...so think about that.

Next, in discussing the Woodstuff hulls. I actually owned both Larry's 32" and the 28" (His actual hulls). Larry's 28" was an older design of the Woodstuff line without the secondary pads, and I just happened to own the newer 28" with the secondary pads before purchasing Larry's. I can say the newer model performed better with the secondary pads. The one without felt like it was struggling to free itself of the water. It always felt kinda sticky. The 32" was just plain fast and handled it great, and it turns great. The 32" Woodstuff, I can honestly say is one of the best all around hulls I have owned as its big enough to handle rough conditions and 5s power. Now, I ran all mine with FE setups, and I am pretty sure Larry's were Nitro, and maybe that lead to his opinion in how he liked it running. Again, these are opinions and my experiences.

Finally, why I use the secondary pads. The secondary pads on my boats, and the Woodstuff hulls, help them out because both the hulls use wide primary pads and larger sponsons than that the typical other hulls on the market. Mike Crawford uses large sponsons on his hulls because of rough water conditions he experiences up north. He found a larger platform could complete races better in high seas. He added secondary pads to free up that surface area on the wide primary pad so the boat could regain speed in the straights and not be a burden of its own design. My purpose for wider ride pads is simply because my hulls start out as FE hulls, and then they get back converted for nitro. Not the norm in the market. I have tested many different hulls and did not like having small sponsons carrying around battery weight. I felt a larger platform under all that weight was a good idea, so a wider sponson was the choice. Like Mike Crawford at Woodstuff, I needed to free up the large primary pad, so a secondary pad was installed. This also makes the hull more efficient in the straights as well, and anyone that runs P-Limited knows efficiency is how you gain an edge with that class of hull. You are limited to your power plant, so you have to gain advantages in other areas. Now, it just so happens the Nitro version of the 295 is currently in position to win (Or may have if they do not do a makeup race for the last race that was cancelled) District 12 with stock power. The boat was really fast and people have made mention it looked like it second staged down the straights. I have a feeling that was the boat popping up on those secondary pads and becoming more efficient and faster!

I am currently testing a new design hull that actually utilizes secondary pads theories even more and some other ideas I cannot discuss at this time but I will say its looking good so far. Lots and lots of testing left to do.

I hope this helped enlighten those that were interested, and didn't offend anyone that disagrees. Again, these are my views. They work on my boats, so I use them, not trying to push anyone into anything.

Thanks, Mike

ML Boatworks

Mike, I and my Son heat raced the 28" boat hard for several season, and won a lot of heats. It was a very forgiving easy to drive boat. In less than ideal conditions it was a stellar performer, In ideal tunnel conditions it could hold it's own.I raced against and beat a few of the newer 28's with the added pad , but I have no personal experience with one to make a decision as to whether or not it improved the performance of that hull or not. The 32" boat was an odd duck for me...Too big for a .21 not big enough for a .45. When set up to Mikes suggested specs I couldn't keep it on the water. If I added enough ballast on the balance point to keep it from blowing off, it was sluggish and unresponsive...All my testing with that boat was in calm conditions running solo, I never raced that hull. I'm looking forward to testing one of your 295 hulls...When my name makes it to the top of the waiting list.

Larry

 

[Kris Flynn]

No one should attack you Mike for explaining your theories and findings...It has been said before, there are many ways to go Fast.

Put a TS3 next to a Lynx, there are 2 totally different designs and both work GREAT, 1 better than the other in an area, the other better in other areas

Kris

 

[Mike Luszcz]

Thanks for everyone's replies. Glad to see such a positive response. Larry, Did you need a nitro 295? I didn't know you wanted to be on the list! Just let me know. There are definitely a lot of great boats out there. I think good setups make the world of difference. Bad setups make anything look bad! lol. Mike

 

[Tim_Duggan]

They all seem to be more prone to hooking and spinning out in the turns than the nitro boats. This can be held off with careful balancing, but the sponsons are probably a little overloaded. I might try a wider sponson with the secondary next season.

Lohring Miller

I'd be very interested to know if anyone has already applied the approach Lohring mentions above and whether it was effective in solving the issues he mentioned.

Mike L, I saw Aaron's new NS295 on the weekend - looks very nicely made!

 

[LarryConrad]

Thanks for everyone's replies. Glad to see such a positive response. Larry, Did you need a nitro 295? I didn't know you wanted to be on the list! Just let me know. There are definitely a lot of great boats out there. I think good setups make the world of difference. Bad setups make anything look bad! lol. Mike

Mike,I don't quite understand why you would expect a negative response from me on the subject of boat design. I did talk to you about a N295 in a phone conversation shortly after your recent career change and you told me you had a backlog of orders to take care of first. Boat setup is vitally important but needs to be tailored to how you run the boat. an extremely fast saw setup doesn't generally heat race well, And a reliable consistent heat race setup usually won't set the clocks on fire at a saw or two lap event.I have only heat race my boats. When I first started racing tunnels my boats were setup very loose and they were plenty fast because the majority of my testing and practice running was done in relatively calm conditions and my boat was running solo. Running in six boat six lap contests I was usually leading or pushing for the lead when my boat ended up upside down, many times only about two laps into the race.As I tightened my setups and began to focus more on how the boat went through the turns and less about how fast it went down the straights my percentage of finished heats increased dramatically, and I even managed to win a few. I have tried a lot of different hulls looking to carry more and more speed through the turns, and I'll be trying more designs yet.

Larry

 

[Tim_Duggan]

They all seem to be more prone to hooking and spinning out in the turns than the nitro boats. This can be held off with careful balancing, but the sponsons are probably a little overloaded. I might try a wider sponson with the secondary next season.

Lohring Miller

I'd be very interested to know if anyone has already applied the approach Lohring mentions above and whether it was effective in solving the issues he mentioned.

I'm going to give this a try by sheeting with ply a gelcoated boat that the sponsons have warped - anyone have any tips regarding bonding ply to gelcoated glass?

https://www.intlwaters.com/gallery/displayimage.php?pid=17433&fullsize=1

https://www.intlwaters.com/gallery/displayimage.php?pid=17434&fullsize=1

 

[Mark Poole ModVP]

Since you are just conducting an experiment there is no need to remove the gel coat. Use some rough sandpaper such as 100 grit to really rough up the gel coat. Make sure you scratch it up nicely where the ply ride pad is going on. Rough up the ply real good too. This may sound strange but I have been getting better bonds when I don't wipe surfaces with acetone before bonding. I think the reason is that after sanding, some resins "glaze over" when wiped with acetone. I use a paint brush to clean any dust off the surfaces and maybe wipe with a dry paper towel.

 

[Tim_Duggan]

Thanks Mark!

What would you recomend to bond with - Epoxy?

Tim

 

[RodneyPierce]

Hey Tim, I have been using 3M VHB tape to bond my test mods to the bottom of my sponsons with. It holds well enough to get a test weekend out of it, but yet if it doesnt work, you can still remove it, and the tape and try something else. Would just have to make sure the plywood was sealed, and smooth on the side your sticking the tape too.

 

[Mark Poole ModVP]

Epoxy would probably be best since one of the materials is wood. But, I have used both ca and polyester resin to glue things on and they hold.

 

[RonShaw]

They all seem to be more prone to hooking and spinning out in the turns than the nitro boats. This can be held off with careful balancing, but the sponsons are probably a little overloaded. I might try a wider sponson with the secondary next season.

Lohring Miller

I'd be very interested to know if anyone has already applied the approach Lohring mentions above and whether it was effective in solving the issues he mentioned.

Mike L, I saw Aaron's new NS295 on the weekend - looks very nicely made!

The comments on secondary ride pads is very interesting. The P spec boats we race started as nitro boats like the VS-1, Top Speed 3, and my modified wood Leecraft XTR-21. They all seem to be more prone to hooking and spinning out in the turns than the nitro boats. This can be held off with careful balancing, but the sponsons are probably a little overloaded. I might try a wider sponson with the secondary next season.

Lohring Miller

Lohring,

I am in the process of building a P-Spec and P Tunnel using the LeeCraft XTR21. I am concerned with the weight as well and was concerned that, what you are experiencing with hooking, would happen with FE on this hull. I have my nitro boat to compare and I am going to try everything I can to maintain the same COG to help prevent this from happening. I know the overall weight may be slightly more but if I maintain the same COG, I believe the two boats will be very similar in performance. I will keep you updated and would appreciate anything that you feel will help another avid LeeCraft boater!!!......

 

[Carl Van Houten]

Ron,

I have found that through talking to all my FE O/B Tunnel drivers that they are finding the same C/G in FE as we found in Nitro. The only difference being O.A.W. Now this is data gained from the Lynx and Shaman. The Warhead is a little different platform and it requires a somewhat more rearward C/G when setup for FE than that of the Nitro version.

Let's see what Lohring says about his guys.

-Carl,

 

[RonShaw]

Thanks Carl. That is very hopeful. I was hoping that would be the case and it sounds like it is. One more thing, who has the molds for the original 360 with the cockpit built into the hull and not the cowling and is there anyway I could get someone to build me one?

 

[Carl Van Houten]

The old Aerotech SR-360 molds were purchased by Jim Iriwin at one time. Not sure of their where a bouts now. That is an old one there. Thoes molds were built around 1984 or 85. They may not pull a straight part by now??? That was a "Low Air Tunnel" It took a screamer O/B to get it up and rolling.That's why it finished a lot of windy races when many others got a big fat D.N.F. under thoes conditions.

-Carl