Power choice Poll

[Willallison]

love the waterjets produced by Mercury, wet-foot, but they won't really conform to our low build-cost and economy aims....

[maarten221]

Well, I'm back from my break, and I see I missed quite a bit!

First off, I'm not what you would call an expert, but I have seen this done before.

Since Price, performace and economy are major concerns, the following setup can be considered:
Diesel Electric

I saw a boat like this in cape town a few years back...

a 30' Trimaran with 2 small honda generators (The size/capacity specs elude me at this time) attached to 2 8" Advance DC Motors - one in each pontoon. As far as I understood the builder (I think it was one of the bacyard type jobs that we all love so much) the motors allowed him to steer the boat more or less like a tank - by increasing or reducing power to each of the motors. I didn't get a chance to board the boat to see the system in operation, but seeing the props on the pontoons intrigued me. Grante O-1 is not a trimaran, but would some similar hybrid setup not make more sense.
I checked at the local walmart and a generator capable of running the 120V DC motor runs about $500 max, while the 8" DC Advance DC motors can be had for around $1500 each. Now I know corrosion might be a factor here and I would love to be able to get in touch with the owner of the boat described to find out how long it lasted.

[wet-foot]

One thing I would consider for this application would be a pair of gas jetdrives.
Perhaps you could find a matched set of used jet skis and rob them of there propulsion systems. One per side. Should not be a major chore to setup a steering system either. Most skis come with taches etc. plus saltwater would not be a major issue. With a 30' LOA you could have a nice set of tanks for ultra long range cruising too!!!! Small jetskis 75hp can be had for under $1,000.

[lakerunner]

Dead heat....... lets start.... I will look for cost comparisons between the tie.
but need to know the power Lets let the cost and efficiency determine use .

[bg1361]

I'm considering buying a pre-owned 2-4 year old fishing boat. I'm considering a twin outboard in a 30'-33' like a Grady White or a twin inboard open diesel like a Luhr's 33' or Topaz 32' or an Albermarle 33'. My problem is, I'm new to saltwater boating and I may be fshing alone alot of the time. Other times my wife and kids would like an easy cruise on the ICW. What would be a good choice in something I could handle and still be able to fish alone?

Do you have a preference of outboard vs inboard diesel in boats of the size? I would love your opinion and would like to research the pros and cons of these motors, but where should I look for more info? Please advise.

Thank you for your help. e-mail: Saveway5110@aol.com

[maarten221]

Originally Posted by wet-foot

One thing I would consider for this application would be a pair of gas jetdrives.
Perhaps you could find a matched set of used jet skis and rob them of there propulsion systems. One per side. Should not be a major chore to setup a steering system either. Most skis come with taches etc. plus saltwater would not be a major issue. With a 30' LOA you could have a nice set of tanks for ultra long range cruising too!!!! Small jetskis 75hp can be had for under $1,000.

You can look at the Kawasaki JS550's. The hulls are usually pretty tired, but the jet drives are sturdy. I've seen JS550's go for as little as $400 - in good running condition. You are correct. These coupled with a low drag, light weight tri will really be economical and should be pretty speedy. What kinda speeds are we looking at here?

[mackid068]

The ultimate method of propulsion is diesel waterjets, but otherwise, a diesel inboard would serve just right.

[maarten221]

I've been thinking more and more about the diesel waterjets. Imagine a Trimaran of around 40' with a large (meaning something like a cat) diesel in the main hull, driving a jet and a generator, and 2 electric motors driving smaller jets in the ama's. With a light enough boat and enough power, it should be an absolute hoot! I can smell a 50kt project a brewin'!

[wet-foot]

As long as you are happy with the rig when complete!!!!!!!!
are you really going to do this or?

[maarten221]

I'm thinking about it. I mean for an amateur boat builder, it would be quite a challenge! It will probably take a few years and the construciton methods will defenitely not be conventional. My main concern is the propulsion. What size waterjets and diesel engine?
The main problem with diesel engines are that they become quite heavy the larger you go. This will require some extensive "outside the box" thinking. I guess ferrocement is out of the question...hehehehe

[mackid068]

Sure, why the hell not? 50 kts!!! YEAH!!

[maarten221]

The slender hull trimaran seem best suited to this design. (keeping in mind total cost and ease of constructions) What materials would you suggest for building such a creature? Plywood, FG, Aluminum or ferro cement?

[wet-foot]

If I was building a one off trimaran my construction method would be cedar covered in glass and epoxy. westsystem is very helpful when it comes to working with their product. Sort of like building large cedar stip canoes. Would sure be easy to build and upkeep would be a breeze. I've seen VW diesel marine engines in Europe don't know if they are available here? I still think adapting jet ski engines would offer the best performance for the buck. Would look at the yamaha 1200 series skis .......... 155hp. these Yamaha models are everywhere and cheap too. Where else can you get a twin jetdrive system "310hp" fo 6k or so!!!!!!!

[PowerTech]

VW rabit diesels were marinized by a company called pathfinder not to bad a motor very high RPM It buzzes alittle much.It's a odd ball I yould try to sell you a yanmar.I found one if you like, here you go. http://lists.samurai.com/pipermail/t...il/003646.html

[maarten221]

Thanks Powertech - but I think a yanmar in the size I'm interested in, is a bit out of my range, greenback wise...

Wet Foot. I agree with the yamaha idea - only problem is, at the current prices for regular gasonline, it would be almost impossible to do any real trips in this boat without breaking the bank. My idea is a little more complex than merely diesel. I've been doing a lot of reading (and some work) on SVO conversions for diesel engines. Basically, you would be able to call this boat a waffle house powered diesel boat. This will allow me to power the boat on a fuel that is essentially free and pollutes MUCH less than regular diesel or gas.