Power option for runabout

[capt jake]

OK, I am going to be working with Sam Devlin on designing a mahogany runabout (he is doing the designing, I provide input).

I am thinking of something in the 17-18 foot range, plumb bow, plenty of tumblehome (take a look at Tom Lathrops 'Scamp'). Obviously S&G but with cold moled mahagany for the finish layer.

In an effort to keep it looking sleek, I am researching poweplants. Rather than hanging an OB on it (which is probably what will happen anyway) I am thinking of one of the jet drive units in the larger PWCs. Key here is 'size'. It has to be small enough to fit in the boat without taking up a lot of room, which would defeat the design priorities.

I have been told that the only unit for sale (aftermarket) is the Mercury Sportjet (175hp). I am still waiting to here from them regarding size, mounting, etc (their site lacks a lot of information). These have the power plant ,mounted right on top of the pump, which keeps the unit short in length, but it also looks like it may be too tall in this configuration to allow us to keep it below the deck..

I am also told that a powerplant out of one of the larger PWCs would have plenty of power, reverse thrust, etc. I cannot locate anybody that sells these units.

Any thoughts, ideas, input, suggestions, other options?
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[rbgarr]

How about an E-Tec Evinrude jet outboard in a covered well.

[capt jake]

Etec is an option; a spendy one though. I should clarify that the use of a jet is 'not' a priority. I simply thought that I may be able to come up with a power plant that is small enough to conceal below a hatch in the rear deck, kinda CC'ish. ;) If all else fails, we may end up hanging an outboard on it. Sam says he needs the power plant picked out prior to starting the major designing, which makes sense to me.

[Paul Pless]

Lots and lots of compromises in going with the jet drive.

They are not very efficient, they generaly use a 1/3 more fuel than a standard prop drive of the same output. You also need to have good access to the intake from the inside of the boat - so that yiu can reach down and clean out the intake. Here in Alabama, I wouldn't dare take my boat accross lily pads, milfoil, or hydrilia. And in the fall, leaves will clog the intake.

Pretty much unless you need to run in extremely shallow water or have a an extremely high powered offshore boat there's not much benefit to running a jet.

Just my .02 after eight years of owning a jet drive fishing boat.

[Bob Perkins]

Capt.

If old time mahogany runabout is what you are going for.. I'd suggest an inboard - there are plenty to choose from and since you are working with the designer - he could make it fit. I'd guess a jet would take up as much space..

While not stich & glue.. have you looked at Glen-L plans?

Take a look at http://www.bronkalla.com (http://www.bronkalla.com/) and my imagestation link in the signature. I'd think a lot of construction would be the same.

Hope this helps - I'm sure you've put a lot of thought into it and I'm probably missing something ;)

[Thorne]

Sounds like a jet drive is not a good idea. But if you *must* check one out, why not contact a shop that rebuilds/repairs PWC's -- they might have a junk Mercury Sportjet they could loan you for measurements or even mounting testing.

[capt jake]

All good thoughts and I appreciate the input.

Inboard: In trying to stay in the 17-18 foot range, it would take up a fair amount of cockpit space. I envision being able to take 4 people out and have rom to move about. Take the kids to the lakes and pull one on a tube, that sort of thing.

Jet drive: I didn't realize they were so fule hungry, good point. Though we don't have a lot of junk to foul the intake, that is definitely a concern I need to think of.

Glen L: Well, that's what started this quandry. I bought the plans for the Malahini, though I like the look and style of the larger inboard models, the Malahini was a comprimise to keep the length down (my indoor storage area will limit the size to 18' max). I have scoured Bronkala's site and have all sorts of inspiration from it.

I work with Sam part time and mentioned the Glen L plans. He stated that he has had something similar on the drawing board for some years now (though smaller). He said he would gladly work on the project with me to reach a design that is more traditional in looks. The price is right ;) and it would add a design to his design catalogue. This is totally new territory for me, if not intimidating, it should be rewarding in the end. :) His present drawing incorporate an outboard motor, which as I said, will probably be the easiest in the final inception. Just exploring some alternatives.

thanks,
Jake

[Bob Perkins]

I think a nice 4 stroke outboard would be best too. An inboard takes up a fair amount of space since you would need to place it more forward than anything else..
I hung out with Sam at Woodenboat School 2 years back. A real nice guy.. Not sure why he hasn't been back since then. He has groupies - same 2-3 guys taking the same exact class (Stich & glue) for 15 years..

Good luck!

[Gary E]

350 Chevy V8
If you REALLY want to RUNABOUT FAST...a Chevy 505

There is NO REPLACEMENT for DISPLACEMENT

[capt jake]

I think he is a little onthe busy side lately. ;) He has had a lot of 'changes'. :)

Not sure why he hasn't been back since then. He has groupies - same 2-3 guys taking the same exact class (Stich & glue) for 15 years..

[Paul Pless]

His present drawing incorporate an outboard motor, which as I said, will probably be the easiest in the final inception. Just exploring some alternatives.


Sounds like a cool project, especially being able to work closely with the designer. How are you guys planning on mounting the outboard?traditionally to the transom, or in a well? I understand some of the aesthetic issues you are probably going through, ie. having a classic mahagony runabout, with one of these new outboards with modern styling sometimes just don't go together well...

Have you looked into a standard inboard/outboard installation or perhaps even a V-drive? I've seen both options work well even with comparitively small 4 cyclinder engines. And there are plenty of new and or used parts parts available.

[Dale R. Hamilton]

Capt Jake: I am building Ray Sergeants 15' sport runabout that has much the same engine requirements. I'm building a marinized 1800cc Subaru automotive engine. Its all aluminun, weights 300 pounds for engine AND transmission, is boxer style horizontal opposed cylinders so it has very low profile. It sits backwards and amidship, the crank turning a heavy belt over the driveshaft. It is on my workbench at the moment, but Ray says performance and economy are outstanding. I paid $2400 for the complete, completely rebuilt engine, with shipping from Colorado Engine Rebuilders. Are you anywhere near Nashville Tennessee so you could come look?

[capt jake]

Thanks for the offer Dale, I would love to come and look, but I am a bit far away for that. ;) I am in Oly, WA. Do you have a photo album of your project? I would like to see what you have done.

As for mounting an OB, it would be conventional on the transom, no well on this design.

[Dale R. Hamilton]

Capt: Look up "Ray Sergeant runabout" in woodenboat #134, Jan or Feb 1997. It has complete description and photo's.

[capt jake]

Hey Dale, thanks for the information. Very informative except how to marinize the starter and alternator (which I know you were delving into a while back). Have you come up with a solution for the starter and alternator?

At the back of the article there was a contest posted. Do you happen to know which issue the winning designs were published in? If you do, you may want to post in Designs/perfect powerboat design; it sounds like the design criteria match what they are looking for in that thread.

[pcford]

I do runabout restoration.....couple things:
1. If you want to build a boat.....great, it's great fun.
2. If you want a boat.....you would be a lot better off economically to restore an existing hull.
Value of homemade new design is not much.

[Dale R. Hamilton]

CAPT- Simple really. I just used a marine alternator- an Arco 60104 51 51 amp and of course fabbed by own mounting plate/tension adjuster. The starter was a new Subaru, marinized by sealing the original drain hole. Fuel pump was a Crusader 47039 horizontal pump. The distributer is electronic with a sealing rubber. Thats really all thats required. The cooling system on this baby is a little involved. Uses the enging water pump to circulate thru a heat exchanger, and a raw water pump to bring in fresh lake water to cool the engine exhausts. Plans call for an oil cooler to boot- but I think I can skate by the extra.

I never saw how the contest developed. Never heard of it again.