Want COI for my stock Suntracker pontoon

The study of the possibilities of your boat does not have to be expensive. Since USCG inspectors will not charge, the total amount does not have to be high. The important thing would be to know the calculations and changes should be made to bring the maximum possible passengers. This increase in passenger numbers is onlyb thing ()obviously) that can justify the investment. Bring the boat up to 12 passengers can be relatively expensive but that cost will not increase in proportion to the total number is achieved.

 

TANSL is correct. The final passenger count is not proportionate to the cost of certificating the vessel. The U.S. Coast Guard does not charge directly for this service. There is a $300.00 annual fee to maintain the certificate. The cost lies in proving that the vessel has the proper scantlings to meet the requirements in the CFRs.

There are also other details that will need attention, such as access to the hull interiors for a complete internal inspection 46 CFR 176.402. Most pontoon hulls are welded solid with maybe just a drain plug. Some sort of hull access will need to be provided. This could be as simple as cutting holes and welding them up, but keep in mind that you will need to provide access every 2 years for regularly scheduled dry dock inspections. The final solution will need to be watertight and will probably need to be air tested.

All hand rails will need to be at least 39.5in high with not more than 4in of space between any of the rails. These rails must be designed to support a horizontal point load of 200lbs. 46 CFR 177.900

Adding internal structure to an existing round pontoon hull to bring it up to ABS rule scantlings would be very difficult. It might be easier to build new pontoons. The added weight of this structure would increase the displacement decreasing the freeboard. Passing the stability test requires a certain amount of reserve freeboard.

All of these reasons are why most certificated passenger vessels are designed from the keel up to meet the requirements. Keep in mind that there are exceptions and waivers that can be made by the local Officer in Charge of Marine Inspections based on the vessels route and service. The Coast Guards role is to facilitate safe commerce not to stop it. That said it is important to remember that the regulations in 46 CFR were, for the most part drafted as lessons learned from accidents and best marine practice. Following the regulations will produce a safe conservative vessel. The Suntracker is a good safe boat and is perfectly suited to what it was designed to do, however it may be difficult to certificate as a small passenger vessel.

 

ABS scantlings rules are inappropriate for vessels of this size. ABS's own limit of their rules is for vessels greater than 79' long. For smaller boats, the ABS rules (and other ship-specific scantling rules) simply result in structures that are way too heavy. Alternative scantling standards would have to suffice, and quite frankly, I don't know of any that govern aluminum pontoon hulls. Some adaptation of the ISO 12215 standards might be possible, and this would most likely be special case engineering.

Eric

 

I do not know the ABS Rules but the "Special Service Craft Rules" by Lloyd's Register I'm sure that serve for calculating scantlings of a pontoon of any material.
ISO 12215 can only be applied to small (6 m to 25 m in lengh) recreational boats, NOT to commercial boats, because they do not consider some solicitations that, for commercial boats, are very important.

 

I agree, however the regulations 46 CFR 177.300 require scantlings to meet one of these standards.

Except as otherwise allowed by this subpart, a vessel must comply with the structural design requirements of one of the standards listed below for the hull material of the vessel.
(a) Wooden hull vessels: Lloyd's Yachts and Small Craft (incorporated by reference, see 46 CFR 175.600);
(b) Steel hull vessels:
(1) Lloyd's Yachts and Small Craft; or
(2) ABS Steel Vessel Rules (< 61 Meters)(incorporated by reference, see 46 CFR 175.600);
(c) Fiber reinforced plastic vessels:
(1) Lloyd's Yachts and Small Craft;
(2) ABS Plastic Vessel Rules (incorporated by reference, see 46 CFR 175.600); or
(3) ABS High Speed Craft (incorporated by reference, see 46 CFR 175.600);
(d) Aluminum hull vessels:
(1) Lloyd's Yachts and Small Craft; or
(i) For a vessel of more than 30.5 meters (100 feet) in length: ABS Aluminum Vessel Rules (incorporated by reference, see 46 CFR 175.600); or
(ii) For a vessel of not more than 30.5 meters (100 feet) in length: ABS Steel Vessel Rules (< 61 Meters), with the appropriate conversions from the ABS Aluminum Vessel Rules; or
(2) ABS High Speed Craft;
(e) Steel hull vessels operating in protected waters: ABS Steel Vessel Rules (Rivers/Intracoastal) (incorporated by reference, see 46 CFR 175.600).


In this cased the best way to go would be to prove that the structure is at least as strong as ABS high speed rules, possibly using the girder strength from ABS naval high speed craft rules.

I have also found that the ABS rules produce a heavy boat at less than about 60’. The big problem is the low welded UTS allowed and meeting the girder strength with the low side height on small boats. The rule was intended for vessels with a large distance between the keel and strength deck. If this distance is too small it can be difficult to get enough section modulus in the longitudinal hull girder section to meet section 3-2-1.1 of the High Speed craft guide without using very heavy longitudinal framing. It can be done but the boat will be heavy.

Obviously in the case of a pontoon boat some leeway would need to be given in this area. The design pressures and panel strength requirements could still be met without too much difficulty. The latest update to the ABS high speed guide has helped by reducing the numbers a bit and allowing use of the High Speed Naval Craft guide. The high speed craft guide is not limited to a minimum length it is applicable to aluminum multihulls up to 328ft.

 

Part Time, thanks, is very clarifying everything you say and I no doubt whatsoever of the correctness of your conclusions. But I have to say that it looks very demanding having to calculate the scantlings of a pontoon as standards for high-speed vessels. In addition to longitudinal strength, I do not think it is very difficult to achieve, local impact pressures suffering a high-speed vessel have nothing to do with a pontoon sailing, exaggerating, at 14 knots. What do you think?.
Another question, do you think the USDCG would not accept calculations according to the Special Service Craft Rules by Lloyd's Register?. Would it be not possible to negotiate with them?

 

I think you and Mr Sponberg are correct, in some cases requiring full compliance with a class society scantling rule is too conservative. Unfortunately for small aluminum vessels it is the best we have. Until the regulations are changed to allow the use of other criteria we are stuck with what is listed in 46 CFR 177.300.

I have seen several successful small aluminum catamaran and mono-hull designs to ABS High Speed all under 40’. The scantlings this rule develops are conservative, but given aluminums poor cyclic fatigue properties a stiffer structure is not all bad. I inspect a fleet of about 70 boats al in the 25-40’ range. They were all built to lighter scantlings than what would be allowed by the ABS rules. They all have repeated stress cracking on welds and plate. The heavier boats built to ABS tend to have less problems. Unfortunately, they are also deeper draft and less efficient boats.

I am not familiar with the Lloyds Special Craft Rules so I do not have an answer for you. I agree that the ISO Standards were not intended for commercial use, but do you think they might be a better choice for small light aluminum boats?

 

All I can say is, I'm sure, the maritime authorities of my country (Spain) never admit scantlings derived from ISO for a commercial vessel.
I do not know if your authorities are more flexible. But when it comes that the differences between these "methods" are so large, there is no flexibility.
We will have to ask the USCG.