Hi all,
 
I have been following several forums and web sites regarding Tow Boat construction.
 
I would like to make mine but to know first about your experiences with round vs. lat bottoms and decide which one.
 
Yoy know better than me examples lke:
 
Star River . flat bottom
Springer: round bottom
and many other models with mixed round/flat bottom.
 
Looking for long runs, maneuverability, control and fun I am not looking for speed.
 
Would you like to share your advice, thoutghs and exerience?
 
Cheers,
 
Iñigo
 

There is not much to talk about.
 
Both are accurate. The real boats come both ways, so either would be accurate.
 
From a modeling point of view:

• A flat bottom is slightly easier to build.
  
• There are plans for a flat bottom on this site, that you can down load for free.
  
• A flat bottom does not require a stand. Four of those little press on furniture bumpers is all that you need.
  
• As I understand it . . . In real life, the round bottom was originally designed to reduce surface contact area if the boat runs aground on say a sandbar. Not a real big problem for a model.

SLA: Symbionese Liberation Army?
 
Why would anyone want them on a boat???
Not me!!!

Quote from nachoo on Jul 6^th, 2010, 1:20am:

 
To the best of my knowledge there are not any springers in the club.  
A few years ago there was a short lived attempt to adapt the ‘polo tug’ as a club boat, but that never got off the ground.
 
As for building a springer class boat, that would be up to you. As for displacement; I seriously doubt that the displacement is any different. There might be more drag, but that would be minimal. A down side to the springer class, is that the class appears to outlaw flanking rudders. Which greatly effect the maneuverability. But then there is nothing that would require you to build anything to anyone else’s spec’s!
 
As for SLA’s: They hold their charge better then most NiMh or NiCad batteries. At one time they offered a much longer run time. Today there are NiMh with 5Ah ratings. Two 5Ah NiMh in parallel would give you 10Ah rating which will outlast a 7Ah SLA at less then half the weight.  
So in the end it all comes down to size . . . And weight. How big of a boat do you want to have to haul around, and how much can you lift?
 
The SLA’s do offer less maintenance though.  
Charge them and forget them. The NiCad & NiMh will loose their charge over time.  
SLA’s do not require any special chargers.  
 
Then again . . . There is charging time.
Charge a 5Ah NiMh at one C, and it only takes an houor.
Change a SLA at anything over .5A, and you risk an explosion. So a 7Ah SLA is going to take 14 hours to charge.
 
 
In any event: From what I can tell, the springer is not designed to use SLA’s, people just choose to use SLA’s because they have the extra room in their boat, and they require more ballast. Not that the design itself requires more ballast, as they are building bigger boats. A Springer the same size as Bob's boat should have the same displacement. Just less room to put everything.
 
 
Hint: Get Bob to post a picture of the inside of his boat!!! You will see what I mean!

I use a 20ah SLA battery in mine.  A cheap way to get a battery this size is to buy a cheap portable jump box starter for cars and remove the battery.  I have never really had any problems with charging.  A cheap motorcycle battery charger works fine.  I am going to guess that the motor you are using will be low current draw so a 5ah or 10ah battery should give you a long run time.  I have two motors in mine and with the 20ah battery.  After 5 hours of running I have about half the battery capacity remaining.  Plus, a 12 volt battery will run all of the accessories you want to add on to the boat, but some may need to be regulated to achieve a lower voltage.