Glen-L.com

I just got my Tunnel King plans from Gayle and Darla. I'm been pouring over the pages like a kid with a new toy. I've had this old mid 70s Merc 115 outboard (6 cyl tower of power) that I've been wanting to find a home for and the Tunnel King has looked like an easier project than the Zip because I wasn't going to have to worry about finishing the deck in fine mahogany or scrounging a windshield. And YES, I'll finish the Zip soon. I was not about to abandon it.

Anywho, this 115 Merc motor had been on a 19ft plastic thing with an open bow so I know the prop will be way wrong for the Tunnel King. Anyone that could help with an idea of speed and props would surely be appreciated.

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Isn't it amazing!! The person that never has the fortitude to pursue his own dreams, will be the first to try and discourage you from pursuing yours.

Hi Dave,

I'm new to this forum and first post but not new to boats. I'm 44 and been in boats thanks to my dad since I was 6months old, yep. LOLLL Been in boats of all types and all speeds including 100 plus MPH but not a know it all, just learning every day like anyone else who's self ambiteous.

I am contemplating on building a tunnel boat myself but not certain yet which one but the Tunnel King is of interest for me as well. I myself might just build a an inline 2 seater purely for high end speed. I have a Yamaha V-4 115 that's 10 years old but not run much and has lot's of potentiel for 150hp plus while remaining reliable.

The 115 6 cyl you got is an amazing power plant that can be tweeked and modified while still being reliable, good choice. For prop selection, well it will depend on the set up and what you really want to do. gear ratio in the lower unit plays a big role for speeds attainable too. That's something you should only look into once you get the boat wet because it's more of a trial thing. Having said all that you could acheive 50, 60mph or more but again depends on the set up and use.

I know of one documented build from this site and will have to get back to you for the link unless someone else beats me to it.

I am also new to the forum, mostly because I am computer stupid. But I have looked at the forum from time to time and sometimes thought I should reply, so here I am. I did a write-up on my still unfinished Squirt in the Glen-L web letter #84. The Squirt was unfinished then and still is. But about your question: you need a copy of the Merc factory prop chart; the one that gives boat size, weight and speed range for available props. Being computer stupid, the only way I can think of to get you one is to mail a photocopy, you know where one licks the stamps and all. Although, we do have a fax at work. Let me know.

Dave ,

I'd build the boat and try the prop you have to establish a base from which to work.

I'd guess you'd probably need in the 21-23" pitch range on that set-up(just a wild guess).

More important at this time is the transom height vs shaft length.

Is this an old 15" or 21" shaft length? And what is the boat transom height?

I believe most tunnels are run with the "bullet"(or prop shaft)of the lower unit running even with the bottom of the sponsons.

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

Try this site for more info:

http://www.screamandfly.com/home/

they have a great forum

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

I run a 23 cleaver on a 20ft Rib and a 115hp pushing 55mph and no I haven't used the yamaha chart because it's useless. Too many variatians between hull types, set up and so on. Gear ratio, LWP (nosecone), setback, engine height and way too many choices in props. Propshaft centerline varies a lot again depending on set up.

Having said all that the best drag and or sprint prop choice right now is the cleaver prop from Yamaha. Check out the Scream & Fly website as mentioned above and do a search. The guy's overthere really love them but their not cheap and run around $750 stock. Should have one that fits on your 115 just need to figure out the thrusters spacers.

Cheers
John

Dave,

How fast do you want to go? The prop you have may get you there.

The series in the webletters, the guy was doing 70+ in a Tunnel King with 120 hp, http://glen-l.com/weblettr/webletters-1/wl8-tkg2.html

I'd be thrilled with 70mph. I've been in boats faster than 80. It seems at 80mph and above, the concentration required to keep the boat running straight without taking a quick turn sideways, or controlling chine walk or otherwise keeping the boat under control, is so intense that the fun of it starts falling off. I'm happy with 70.

_________________
Isn't it amazing!! The person that never has the fortitude to pursue his own dreams, will be the first to try and discourage you from pursuing yours.

In a 16' outboard-driven hull 50 is fast, 60 is very fast, 70 is to the point where you are really balancing on the head of a pin. Beyond 70 is to the point you need to evaluate the risks involved. You need to be sure you understand the consequences of even a small mechan failure will be bad... possibly very bad. But more, you need to make sure everyone you care about also understands and is willing to live with the risk. Ya, I hate to be a wet blanket, but falling out is really not allot of fun at any speed. Taking a powder at 80 while wearing Bermuda shorts, sandals, and some cheesy Hawaiian shirt is going to be an exciting day. (well, at least for the sheriff's recovery divers )

With the TK I would worry more about a blow-over than chine walking. Planning to run that hull over 70 is going to take some work on aerodynamics. The learning curve is going to be sharp.